Professor Charlotte Clark, Professor Anna Hansell and Dr Antonio Torija Martínez.

Q1 The Chair: It is a great pleasure to welcome our witnesses to the committee’s first evidence session in our new inquiry into the effects of artificial light and noise on human health. Today we are focusing on noise and we have three witnesses: Professor Charlotte Clark, professor of epidemiology at St George’s, University of London; Professor Anna Hansell, professor of environmental epidemiology at the University of Leicester; and Dr Antonio Torija Martínez, reader in acoustical engineering at the University of Salford.

The session is being broadcast on parliamentlive.tv and a full transcript will be taken and sent to you shortly after the session for you to make minor corrections. If there is anything you think of or any data that you do not have with you that you think might be useful to us, we would be very pleased to hear from you after the session and have that submitted as formal evidence to us. That often proves very useful to us, so if you do think of anything, it will be very much appreciated.

To get us introduced to this session, could you each give us a brief overview of some of the basic questions? First, what do we mean by environmental noise, what are its main sources and how do we measure it?

Professor Charlotte Clark: I will leave the technical aspects of noise to Antonio, because that is his field as an acoustician, but from the health point of view we use the term “noise” to mean any unwanted sound. There is often a mix in the field and both terms are used, but noise tends to focus on what we think of as a negative and unwanted aspect of the sound.

The main sources cover transportation noise—aircraft noise, road traffic noise, railway noise—but there are other noise sources that we have not researched so much that are also quite important: things like industrial noise, entertainment noise, noise from leisure activities. There is also a whole host of new noise sources coming along like drones and urban air mobility, which are all different from what we think of as noise sources, different sound signatures, that we are used to. They are also environmental noises that we think will become quite important.

The Chair: Our focus is probably not on the noise that people are exposed to in their jobs, so not the industrial noise that the Health and Safety Executive might be involved with—

Professor Charlotte Clark: Occupational noise.

The Chair: —yes, occupational noise. Our focus is very much on the noise that we might all be unable to avoid if we go out into the environment, or stay indoors indeed. Those are very interesting points about the new kinds of noise; as you say, things like drones. I went to a lecture recently about urban air mobility, and there are some quite frightening prospects for everybody. So your thought about future noise is very interesting.

Professor Anna Hansell: Antonio will, I hope, give you an overview of some of the technical details, but it is worth noting that the noise levels that we are talking about when we look at noise and health are much lower than the occupational noise levels that give effects on hearing.

We use a number of metrics, but a lot of the metrics were developed specifically to look at noise and sleep. There is a limited amount of research looking at more interesting types of metrics that might have better relationships with health than the absolute noise level. We know that noise from different sources has different characteristics; noise from aircraft, for example, has an envelope of sound where the level goes up then down. There may be different biological reactions to a noise that is coming towards you rather than one that is going away from you. If you have noise at the same level over a period of time, you may have less of a biological response to it than a noise that varies. They are all areas that are ripe for more research.

Another issue to do with noise in the epidemiological studies that I look at is that we often find that noise at night has a more consistent or sometimes a stronger response. It is not very clear whether that is because noise has a particular biological action—one of the modes of action that I hope we will get on to in the next set of questions—or because, if we are modelling noise to people’s homes, they tend to be there at night and not so much during the daytime, so we may have a better measure of exposure there.

The Chair: Thank you very much. At the end of session we will ask you to tell us where you think there are gaps in the research, but the other thing that we are very interested in is where the research is telling us that we need more policy or different policy. It would be very helpful if you could bear that in mind as you are talking.

Q2 Viscount Hanworth: Noises often alert us to danger, and then there is a physiological reaction. Can you categorise the effects of noises according to their tendency to alert us to dangers? We may have very atavistic tendencies in this respect. Is there mileage in that kind of idea?

Professor Anna Hansell: Definitely. There may be more questions on biological mode of action, but that biological response is important, because it wakens you from sleep or gets you into a less deep sleep, and it causes your blood pressure and heart rate to go up. It is really important. It is more likely to happen if you get a sudden loud noise, which is likely to grab your attention and cause that physiological response. There are other potential mechanisms for noise to do with annoyance and sleep disturbance and potentially from non-specific stress on the system that might affect or depress the immune system, for example, but that has been much less researched than the other three aspects.

Viscount Hanworth: We seem to have strong filtering mechanisms that can lead us to ignore all sorts of things that do not signify danger.

Professor Anna Hansell: We might ignore them but…

The Chair: Can we come on to that later, because otherwise we will pick up some of the questions that people are waiting to ask you a bit further on in the session?

Dr Antonio Torija Martínez: As Charlotte said, noise is unwanted sound. Sound is acoustic pressure [1],[2]. Think of an aircraft, or any machine. Even as I speak I am producing sound waves which cause perturbations in the pressure field here in this room. That is basically what we know as sound.

We are working in two different areas for environmental noise. We are working on understanding how a machine, an aircraft, produces sound. We have very sophisticated models to quantify the sound on the ground produced by an aircraft taking off at Heathrow Airport. At the same time, we have colleagues like Charlotte and Anna working on the effect of that sound on people.

I like to think of noise as relevant, because someone is exposed to it. If you think about noise as energy, a really small amount of acoustic energy is produced by an aircraft. The key thing here is that even a small amount of energy will influence quite a lot of people on the ground. That is why we are working on two different areas: the emission of noise and the reception of that noise.

We have two different ways of assessing environmental noise. One is using specialised equipment, which we can see around airports—sound level meters, for example, very accurately measuring the amount of acoustic energy received on the ground, for example from aircraft operations. Sometimes we are limited to being able to locate equipment only in specific areas, so we need to rely on models allowing us to estimate and assess noise in wider areas—around Heathrow Airport, for example.

Something interesting that is happening in the UK at the moment is the updating of the environmental noise models for road and railway noise. The previous models—CRTN for road traffic and CRN for railway noise—were from the 1980s. A group of researchers in the UK are currently updating those models, which is quite useful for us as researchers, because we probably need more state-of-the-art models to work with. So that is appreciated.

We try to connect the noise emission with how the noise is influencing people by using a number of noise metrics that try to represent the relationship between the noise that you are exposed to and your reaction to that noise. We do not have time to go through all those metrics, but basically they try to account for the amount of acoustic energy and the time you are exposed to the noise, and, in some cases, the number of events you are exposed to. I guess that links to a later question about the most annoying sources of environmental noise.

The Chair: Thank you. Baroness Neuberger will pick up on that issue of annoyance.

Q3 Baroness Neuberger: I ought to declare an interest as chair of University College London Hospitals NHS Trust and Whittington Health NHS Trust, as I am quite interested in noise in hospitals, which can be very annoying.

What is the evidence, or is there any evidence, on which kinds of noise are the most annoying; noise from different sources, sustained or intermittent noise—or pitch, because there is some evidence on that? Can you tell us a bit about that?

Professor Charlotte Clark: Annoyance is assessed using an international technical standard, so when we use the term it should, hopefully, relate to people who have used that measure; it does not always. Annoyance is really a disturbance, irritation or dissatisfaction, or a nuisance noise. It is one of the key community responses to noise, particularly environmental noise. If, for example, you had a noise event where everything was at 60 decibels, which is not massively loud but is moderately loud, people would rate aircraft noise as being most annoying at that level, followed by road and then railway. There are differences between noise sources in how annoying people report them to be, but that has to be caveated by saying that we have tended to look at those three noise sources a lot more than the whole range that we spoke of just now. Far less is known about annoyance from other noise sources.

The Swiss have led the research in intermittency, how intermittent the noise is, with their SiRENE study. They managed to create a metric across their whole population. They modelled noise exposure, but they also knew whether it was made up of intermittent events or a very constant noise source. Intermittency did not alter annoyance for aircraft and railway, but did for road traffic; more constant road traffic was rated as more annoying. Intermittency is quite a new area in the field, and when people look at sleep they see different ordering of those noise sources. What I have spoken about applies to annoyance, in that aircraft is more annoying than road and railway. It is a different pattern for other outcomes.

Baroness Neuberger: There is very little on things like extremely loud music or anything like that. There is just not much known.

Professor Charlotte Clark: There is less known. We have national surveys. I think the last one was from 2013. I can certainly send through how annoying different sources were. We can provide a bit more detail on that.

Baroness Neuberger: That would useful. Thank you.

Professor Anna Hansell: My research field is not directly about annoyance but looks at the physical impacts of noise on health. Generally, annoyance has been treated on its own, but there are now some studies suggesting that it might interact with the actual noise level. The noise level has an effect, but the people who are annoyed may have slightly higher effects. There are not very many studies on it. There is also another characteristic called noise sensitivity, which is quite well recognised. Probably about 30% of people are more noise sensitive and are more likely to get annoyed by noise.

Baroness Neuberger: Do we know why they are more noise sensitive?

Professor Anna Hansell: There is certainly a genetic component to it and it seems to be related to anxiety trait. It is possibly a survival advantage for your group if somebody is a bit more sensitive to noise!

Dr Antonio Torija Martínez: From an acoustic point of view, aircraft, road traffic and railway produce a significantly different noise. With road traffic noise—for example, from a highway—you have a very constant, low-frequency rumble noise.[3] With railway or aircraft noise, you have sequences of events.

You made a point about the level and duration of the event, but probably also the pitch. We have found that high-frequency or high-pitched sounds are perceived to be more annoying. Even the high-pitched, high-frequency noise from an aircraft getting to the population from miles away will still be perceived as annoying, so it will probably be one of the causes that is perceived as more annoying.

Other than these acoustic factors, we also need to account for all the non-acoustic factors that will significantly influence noise annoyance. Professor Clark and I recently did a study for an airport in London to advise on the fair and equitable distribution of aircraft around an airport. It was quite challenging, because even accounting for the health or acoustic metrics, there is always a component that we classify as non-acoustic factors that should be considered. We need more research in order to develop the methodologies to account for non-acoustic factors and understand how they influence noise annoyance.

Q4 Lord Krebs: Could one or more of our witnesses tell us about the reliability of measuring annoyance? It is a very subjective phenomenon and I wondered how repeatable it is, whether there are any physiological correlates, and what other justification one can use for measuring annoyance as an objective measure rather than a rather subjective one.

Professor Charlotte Clark: I led the revision of the international standard on annoyance. You are quite right to raise this. In the past, there were issues about how annoyance is measured, because the measure is used internationally. In the late 1990s, an international group set up an assessment of how you assess annoyance. There are standard questions and a whole standard methodology behind that. It is a long-term measure, so we tend to ask you over 12 months. We say, “In the last 12 months, while you were at home, to what extent were you bothered, disturbed or annoyed by noise from aircraft or road traffic?” This question has been used in all our previous noise surveys for the past 10 or 15 years and it is used internationally, as I said.

It is scored in a certain way that gives you a measure called “highly annoyed”, which is what tends to be put forward in policy and in guidance. We predict in your population or for a new development how many people would be highly annoyed by that exposure or a change in exposure. In the last revision of that standard, we standardised how highly annoyed is scored, because we have used it for the past 15 years and it has been different. We are very much in the field trying to standardise so that all annoyance is measured in the same way. So it is measurable, yes.

Lord Krebs: How repeatable is the measure? If you measure the same person and ask them over two time periods, do you get the same level?

Professor Charlotte Clark: That would depend on whether you felt that the person’s exposure had stayed exactly the same, but I will go back to the original development and find the data that looked at that when they set it up. It should be quite repeatable. If people’s noise exposure has been the same, there is no reason to think that it would differ over time. We do not have data that suggests there are huge changes in it over time, and I can certainly find you some evidence on that and provide it to the committee.

The Chair: When I was on the Airports Commission, some of the evidence we had was about aircraft noise. One of our witnesses suggested that your perception of the noise from an aircraft differs if you can see the aircraft. If you could see it flying overhead you would be much more likely to be annoyed by it than if you could not see it. Is that a confusion in this annoyance issue?

Professor Charlotte Clark: It is probably true, but I am not aware of any empirical evidence where that has been looked at. That is not to say that it is not out there.

Dr Antonio Torija Martínez: I have not seen anything conclusive on that. There are road traffic noise studies showing that if you do not see the source, and therefore, you do not know what the noise is, so you are more annoyed. But, I do not think there is any conclusive evidence on that.

The Chair: The other quick question is on the alarm signals in aircraft cockpits. The extreme ones have a female voice. Is this because they are a sexist bunch and they think we nag, or is it genuinely because that higher-pitched noise is more irritating and more alerting?

Baroness Neuberger: Be careful as you answer.

The Chair: Is there any evidence that it should be a woman’s voice?

Dr Antonio Torija Martínez: I do not think there is any evidence of it being a woman’s voice. It is probably about having a high-pitched, clearly detectable alarming sound or noise. I do not think it has to come from a woman. It is just basically high pitched and detectable sound we need. I do not know why it is usually the voice of a women. I do not have any evidence on that.

Q5 Lord Sharkey: I was very pleased to hear about this international standard for annoyance and wondered whether it could be extended to diplomacy as well as to noise measurement.

Taking a point that Lord Krebs is making, how do you factor in variations in tolerance? When people say, “I’m a bit disturbed or highly disturbed” or whatever, how do you disentangle annoyance from levels of tolerance?

Professor Charlotte Clark: Can I ask what you mean by “tolerance”? Do you mean individual factors that might influence—

Lord Sharkey: What I had in mind was two different people exposed to objectively the same kind of noise giving completely different answers about how annoyed they are.

Professor Charlotte Clark: We know that sound accounts for only a small proportion of the annoyance we measure. Antonio spoke about non-acoustic factors. There is a whole range of factors—individual factors such as your age, your biological sex, if it is airport noise your attitude to the airport, how irritated you are, what it is disturbing, if you cannot hear the television or the radio. When you use the international standard you also collect data on these other factors so that you can take those into account when you are looking at the annoyance. We try to measure a whole host of things in our questionnaire as well as the annoyance, and then we adjust the analysis for them. There is a lot of work going on trying to standardise those other factors as well internationally.

Dr Antonio Torija Martínez: There is currently a group developing a new ISO standard for non-acoustic factors so that we have a standardised methodology to deal with all that information about non-acoustic factors in the study of noise annoyance.

Q6 Baroness Northover: This question follows up on the uncertainties in this area. What are the major impacts of environmental noise on human health that we know about and are most confident about? Are there potential impacts for which the quality of the evidence is currently low but where you feel more research might change our view?

Professor Anna Hansell: The first document I would refer to here is the WHO 2018 environmental noise guidelines, which were based on a series of systematic reviews of the evidence as a way to try to ensure that we have identified all the appropriate evidence and combined it in a rigorous fashion to come to conclusions.

There is obviously good evidence for annoyance and for sleep disturbance. There is now good evidence for impacts on cardiovascular disease; the strongest evidence is on ischaemic heart disease, that is, heart attacks, in relation to road traffic noise. There is some evidence on metabolic impacts, for example diabetes. Anything else has a much lower weight of evidence, but there are suggestions that there might be impacts outside the cardiovascular system. Some studies have looked at cancer, although the findings have been quite inconsistent. A few studies have looked at noise and respiratory disease.

To understand this, you need to think about the biological impacts by which noise might be affecting health. We have talked about annoyance, which is very interesting, because it is not just due to the noise level. Some processing of the noise goes on in how annoyed you get with it. There are impacts on sleep, and we know that sleep is very important for all sorts of restorative functions and cognition, but also more physical things like your heart health and heart function and the immune system. There is the fight and flight response, which we talked about earlier, in how your body responds to a noise. That seems to be independent of the other two factors.

There is a small number of experimental, or what they call quasi-experimental, studies. One study took measurements of blood pressure every 15 minutes overnight in about 140 people who live near airports, and found that, if an aircraft went over, the blood pressure and heart rate would go up in response to that but the person would not necessarily wake up. So, it can be independent of people waking up. There is a nice series of studies from Germany by Schmidt et al, who played aircraft noise in people’s bedrooms overnight. When they measured their cardiovascular function the next morning they found that it impacts on biomarkers but also on responses of the small blood vessels. That is interesting in terms of biological plausibility.

The fourth area is what I call the non-specific stressor, which is the area there has been the least research on. The most research is on annoyance, then on sleep, then on heart disease, and there is a lot of attention to this now in cardiology journals. The least attention so far has been paid to the general stressor effect, which is quite interesting and might account for some of the associations with respiratory disease—for example, whether it makes you more prone to respiratory infections.

I will submit something in writing about what we mean by low-quality evidence, which you will have come across. A whole rating of evidence is used to help assess this. I think that is it.

Professor Charlotte Clark: I will not repeat what Anna said. We have good evidence of the effect of aviation noise on children’s learning, and we include that in health because obviously learning is important for your health and your life chances. One area that we do not have good evidence for is what I call mental health, well-being, quality of life. This is increasingly a concern of communities, but we have not studied this well at all in the UK. We have not been able to get funding to look at that, and that is an area that we should focus on.

Railway noise is another area where it would benefit policy if we did some work. We often talk about it in the same terms as road and aircraft noise, but there is far less evidence on the effects of railway noise. We often beg and borrow evidence from other noise sources and plug them into our assessments for railway. We have good evidence from studies conducted overseas, but we do not have the good study of road traffic and annoyance that we need for policy in this country. We have not done a big survey where we have looked at road and rail noise and annoyance. We did that for aviation in SoNA 2014, and the CCA is going out into the field to update aviation noise.

Another area that I think we could benefit from doing research on is neighbour noise. Within the field I can probably say that we very much ignore neighbour noise. It is methodologically complicated, building regs get involved, everybody is living in a different sort of situation, but it really is a noise source that impacts on people’s day-to-day lives and we need to start to tackle that as an area.

The only other thing, and we might come on to it, is that we do not have good studies of interventions where we change the noise exposure, or we try to, and then we assess how that impacted people’s sleep, annoyance, cardiovascular responses.

Viscount Hanworth: Rail noise affecting rail passengers or affecting bystanders? If I can give evidence, when we were running on rails with fishplates, that noise had a very calming effect.

Professor Charlotte Clark: Yes. I am thinking more of residential—people in their homes and trains passing by.

Viscount Hanworth: I can tell you why I think that had a calming effect. It was a return to the womb. It is a heartbeat.

Dr Antonio Torija Martínez: I think we already have very comprehensive answers from Anna and Charlotte. I will add that with the whole process of the modernisation of aerospace in the UK, there will probably be people who are newly exposed to noise. I think we need evidence to see how people respond to that new source of noise affecting them.[4] We do not have the evidence, and studies focusing on that would be very beneficial. I think we have a question about that later.

With the new sources, it is quite likely that we will have a transition towards electric mobility. That will probably be the most radical change in the soundscape we have experienced. We will experience going from the engine noise of road traffic in cities to basically no noise or just some high-pitched sound produced by electric cars. That will be quite a significant difference that probably alters all the evidence for road traffic noise.

The Chair: Can we leave that question until later? Otherwise the person asking that question will not have anything to ask you. Our expert adviser, Professor Foster, would like to come in.

Professor Russell Foster: One question I had was that the assumption has been that individuals from a lower socioeconomic group will be exposed to greater levels of noise. Therefore, how do you disentangle the other associations with lower socioeconomic groups, such as higher rates of type 2 diabetes, cardiovascular disease. How can you factor those two things in?

Professor Anna Hansell: I will start with the first aspect: is it actually documented that more deprived groups have higher levels of noise? The answer is that there has not been very much research on it. I have been involved in some research in London and we did find slightly higher road traffic noise in more deprived areas, as measured by the Carstairs score [5], which is derived from the census. Aircraft noise is more difficult. We are currently doing a study around London Heathrow and we do not find a consistent relationship with measures of deprivation. It differs depending on which measure you look at. We have looked at three different measures. I think Heathrow is a unique type of airport in its proximity to a very large city with very mixed areas, so it may not be the same in other areas of the country or in fact in other countries.

How do we disentangle? That is a common question in epidemiology. Any decent epidemiological study will look really carefully at what these correlated factors are, including deprivation. It will have a good measure of it and it will adjust for it in a statistical analysis. What we do as good practice in my group is to present results before and after adjustment, so that you can see what the difference is when you make the adjustment for deprivation. It is possible to disentangle if you do the appropriate study design and analysis, but you never just rely on one study in epidemiology; you look across a number of studies. You would look for consistency across studies in different areas, which may have different mixes of what we call confounding factors, which are the factors that give you high rates of disease as well as factors that might give you higher exposure. We would look for coherence across different types of studies. For example, if I am looking at long-term aircraft noise exposure around an airport and see an association with cardiovascular disease, do I also see an association with short-term exposure to noise, where that is biologically plausible?

We are currently carrying out a number of studies to look at that. We are looking not just at hospital admissions and mortality but at blood pressure and biomarkers of exposure. You would look across that range of studies and ask whether there is a plausible association, thinking all the time of the other factors that might be influential—ethnicity, deprivation, biological sex—that might modify the associations.

As well as looking at the adjustment, you are also looking at whether these might effect-modify. In fact, my experience in 25 years in epidemiology is that the deprivation is likely to modify associations such that you have a stronger response to an environmental exposure. I have done a lot of work on air pollution and we can see that. The field is much less developed in noise epidemiology, but it is quite important to look at whether there is this interaction.

Professor Russell Foster: To be clear, you would say that there is not sufficient data to correlate lower socioeconomic status and high levels of noise pollution.

Professor Anna Hansell: Not currently, no. It can be quite difficult, because you need to think also about the indoor exposure. If you have deprived areas with lower-quality housing, you may well have higher exposure, not necessarily because the levels outside are different but just because of the housing quality.

Professor Russell Foster: That is really interesting. Thank you.

The Chair: Professor Clark, you mentioned the effects of aviation noise on children’s learning. Do we have any evidence more generally about the impact on children’s health and development? Do we have any from other forms of noise—road noise or railway noise or whatever?

Professor Charlotte Clark: Yes, there is evidence for some other effects. We think that children’s cognition generally is affected, but we do not see it consistently across all the sources and different cognitive outcomes. Reading shows a consistent effect, but there are other studies showing effects on long-term memory, short-term memory, things like that.

Another consistent effect is aviation noise and road noise on hyperactivity symptoms in children—it is not a clinical diagnosis; it is measured using a symptom scale—but the effects are really small. There is a whole debate about whether that is a clinically important effect that we observe, but we have seen that consistently across studies. So there is evidence for children having cognitive and mental health psychological symptom effects and annoyance as well. I can send you some papers with that evidence.

The Chair: When we were being briefed we were told that quite often some of these effects are small, but because it affects a large number of people it is therefore potentially a very big effect.

Professor Charlotte Clark: Yes. I have published on the hyperactivity effect, but I am still slightly concerned about how small the effect is. You are right that, when we think more broadly about some of these effects on cardiovascular and sleep, huge populations are exposed, so these effects can be quite important at a public health level.

Q7 Lord Sharkey: When we think about the main mechanisms by which environmental noise impacts human health, can we say which health effects are the most important? There is stress, disruption to sleep or circadian rhythms, and maybe others. Is it possible to do some kind of ordering of those mechanisms?

Professor Anna Hansell: I do not think anybody has tried. I will send through a reference of some of the biological mechanisms. They are very interrelated; if you have an annoyance that is activating your stress responses, so is your physiological response to noise, so your sleep might well be disturbed. It would be quite tricky to easily disentangle them, and nobody has tried so far, to my knowledge.

Lord Sharkey: Can tolerance be acquired? We know that noise, and the reaction to noise, is mediated by psychological pressures, but to what extent can people learn to tolerate noise, and does this actually happen? Do people get used to it?

Professor Anna Hansell: They can, but they can also be sensitised to it. Even if you do not react to it on a conscious level, your body will still have a physiological response. It has not been very well studied in relation to the relationship with health effects.

Lord Sharkey: Do we know whether there are sectors of society—we talked about social class a moment ago—that are more tolerant or less susceptible to intrusive noise? Is it possible to make that kind of generalisation?

Professor Charlotte Clark: We have a bit of information on this. If we look in national surveys, the group in their 20s are far more tolerant, to use your term. They are less annoyed by noise and more up for the vibrant life, sort of thing, so you see these differences. Annoyance tends to peak in your 40s as you come into middle age, and as you get older and perhaps happier and more relaxed with the world, you are less concerned with noise. Women tend to report slightly higher levels.

Focusing on annoyance and thinking about where we have data on this, it is quite a challenge, when you are doing things that I have worked on, such as trying to assess the noise and health effects of the expansion of Heathrow, to assess how you can use that in an assessment to help you make decisions. There is some evidence that there is a difference for different age groups and by gender.

Lord Mitchell: It seems to me that there are noises that people like and noises that they do not like. You can think of music most of all; somebody else’s music can be unbelievably annoying and you cannot sleep, but to the people there it is wonderful. Are there any measures of differences there?

Professor Anna Hansell: There is a concept called soundscape that Antonio might want to come in on. There is a field of research that looks at the soundscape as a whole rather than the individual noises. Natural sounds like water running or birdsong can mask or attenuate the annoyance that people feel with traffic noise, for example. There are a number of nice articles on thinking about city landscapes in a more holistic way and how you might live with the sounds around you. It can modulate the effects if you have pleasant sounds playing.

Dr Antonio Torija Martínez: Before I talk about soundscape, as Charlotte mentioned and you mentioned just now, Lord Mitchell, if you listen to music at home I am sure you value that music positively, yet your neighbours might be annoyed because they are trying to read, so your music it is just noise for them. That is an important concept to take into account. For aircraft noise, a German professor came up with the figure of only 30% of noise annoyance being related to acoustic factors. Everything else is non-acoustic factors or contextual factors and so on.

With soundscapes, we are trying to stop focusing on the negative sounds—noise—only and trying to design cities in a way that maximises the sounds that have a positive value for us. That is why we are trying to bring nature sounds, water sounds, any representative sound or historic sound into cities. We are trying to minimise all the negative sounds that we call noise—road traffic and so on. That is part of the process that we are in at the moment. I was planning to talk about this later.

There is a new initiative in acoustics that we call perception-driven engineering. We are trying to embed acoustic factors—how people respond to noise—at the beginning of the design cycle of any machine, any transportation system. It is a change in the way we are operating, whereby we try to minimise the noise but at the same time try to maximise the sounds that we perceive as positive for us.

Lord Rees of Ludlow: Obviously stress is a consequence of any annoying noise, but if it is a noise that you can interpret, it has meaning, surely it may cause much more stress. An extreme example is a baby crying, but if there is an ambulance outside your block of flats or the aircraft going past you is making a funny noise, they are all kinds of things that may worry you more. It is not the decibels; it is the concern. If you think of what may keep people awake, surely the interpretation of the sound matters. This is the converse of birdsong and so on being relaxing. There may be things that are the reverse of relaxing and it is the nature of the sound rather than just the volume that matters. Do you have any comments on that?

Dr Antonio Torija Martínez: You are absolutely right. Living near a hospital, we can hear the sound of a helicopter and know that that helicopter might be bringing someone to the hospital, but our perception completely changes if we hear exactly the same sound (i.e., helicopter) but we know that it is just a football player going to training in the morning. It is completely about how much value that sound is bringing us. The perception of that sound is important and something to take into account.

Baroness Neuberger: Coming back to your soundscape thing, are you saying in a sense that you are trying to create a soundscape that people will generally find less annoying in a whole variety of ways? I am quite interested in how you factor in all that stuff.

Dr Antonio Torija Martínez: Rather than act only at the end of the process doing traditional noise reduction, which in some cases is probably pointless because dBs are not the only information to take into account, we are trying to be proactive and add perceptual factors to the design of soundscapes. We need to understand the value of the different sounds that you are exposed to. We want to try to conserve, preserve, maximise those positive sounds if possible, and try to reduce, minimise, abate any other sounds that are not bringing any value but are basically noise for the majority.

Of course, there will be different considerations. For me, the sound of a Harley-Davidson could be a beautiful sound. Probably for everyone else in this room it is just noise. It is part of the process, but we have three standards already and a fourth one in process to help the acoustic community to design and assess our soundscapes.

Baroness Northover: It would be really interesting to see how you have done that in order to try to disaggregate bits of it.

Dr Antonio Torija Martínez: I can provide you with something.

Viscount Hanworth: With my flippant remark about music, some kinds of music engender solidarity in certain social groups, and by that very token they pose a threat and cause anxiety in other social groups. It can have a very differential effect.

Professor Charlotte Clark: A lot of this is about control, about how much control. You might even like your neighbour playing Taylor Swift loudly all the time, but just not at that particular moment. It is a really complex area. Although a lot of your response to noise is biological, the psychological side is really about control and things like that. That is where building regulations can become quite important, because you can often find yourself having no control over exposure to some environmental sources or neighbour noise.

Q8 Lord Wei: I was struck by what some of you said about the relationship between noise and how you interpret that noise. It reminds me of linguistics, in that noise in a sense is like words that you could associate positively or negatively based on your almost preprogrammed-from-birth proclivity to associate sounds with certain meanings.

I am also curious about whether, as technology to analyse brain scans has become cheaper, work is being done to look at the internal neurological changes that happen when people are exposed to noise. Essentially, is work being done to look at other approaches that are slightly more interdisciplinary than the standard approaches that you have all mentioned, which have limitations—surveying and measuring environmental noise but not looking at the interior action going on in a person’s brain?

Professor Charlotte Clark: There are a few studies coming through on brain imaging. Actually, it is an area that I am going to try to get some funding on. It is definitely where the field is at: trying to look at how people respond to noises in brain activity. There are a few studies. I will put those into the evidence so that you have them. It is not a field that is well developed yet, but it is certainly possible to do and we are developing plans.

Dr Antonio Torija Martínez: There have been some studies already—not a lot—with probably not very conclusive results so far. The problem is also that you are bringing people to a lab, and a lab basically has very controlled conditions, so it is really difficult to translate to real life conditions. They are not getting conclusive results, but in any case, it is very difficult to get anything to translate to real life. I hope, Charlotte, that you can bring some useful evidence on that.

Professor Charlotte Clark: Yes, I think it will be a good way to look at the mechanisms in a bit more detail, which is an area that traditionally has not been well researched.

Q9 Lord Krebs: My question was partly answered earlier. I wanted to understand a bit about how the WHO guidelines on environmental noise exposure for the European region, published in 2018, were determined. I think we heard earlier that they are determined by a systematic review of the literature using standard procedures. So I will accept that question as having been answered and move on to the supplementary question, which is about what the UK Government have done, if anything, to respond to those guidelines.

As I understood it, looking at the summary of the guidelines, it appears that the health impacts of noise are in general greater than had previously been thought, in terms of the impact on the total population impact and perhaps on individuals. Have the Government produced any new policies since those guidelines came out—for example, mapping where people are exposed to noise and developing an action plan to mitigate noise exposure?

Professor Anna Hansell: I am an epidemiologist, so I am not a policy specialist, but from my point of view there does not seem to have been much policy response at all. The UK Health Security Agency noise team has been working on a calculation of burden of disease from noise, which my group at the University of Leicester has been involved with. A paper has been produced and is in revision at a journal at the moment. They are a very small, hardworking team—I think there are three people in it at the moment.

One of the problems we have with noise is that there is no clear policy group to go to. There is no clear government department to involve, so Defra, DfT, BEIS and DoH might be involved, and we do not have an expert scientific advisory group for noise like we do for air pollution. I chair the Committee on the Medical Effects of Air Pollutants. We do not have anything similar to go to for noise effects. We have, say, the Committee on Toxicity for chemical exposure in the environment, but it is not very clear where you go to for noise.

I come back to the burden of disease from noise. One thing we have been looking at is the difference between the standard noise mapping that we inherited from the European Union directives and the UK-specific mapping, which also takes account of noise on minor roads and not just major roads, which the strategic noise mapping does. You find higher noise exposures if you take full account of all the traffic exposures, and that gives you higher estimates of burden of disease.

Lord Krebs: Thank you. Do any of the other members of the panel wish to add anything? That was an extremely helpful response.

Professor Charlotte Clark: Noise sits with Defra; it has to work with the other departments but it has ownership of it. I was quite shocked when I looked at your question and I realised that in October it will be five years since the WHO guidelines came out. We have all been anticipating some response. When I say “all”, communities are waiting for a response and we have not had one.

One of the reasons for that, other than just the difficulties of working interdepartmentally, is that the guidelines were critiqued a lot of the time for their lack of economic assessment. They are purely health guidelines. There is no economic analysis of what would happen if you tried to operate an airport down to those levels. That has caused issues.

Government is also very slow to update any of the policy. For example, transport appraisal guidance—TAG—is used when you want to build a railway or a runway. It has a really out-of-date health impact assessment in it. That is governed by an interdepartmental group. We updated the evidence for it back in 2020, I think, and still nothing has happened. It is a reflection of how long it can take to do something relatively simple like change an exposure response function, to update and have the most recent evidence for what the health effect is within the system. It is all quite slow moving and difficult to influence.

Lord Krebs: Thank you. That is extremely helpful. Can I check one figure that I think I heard? The UK Health Security Agency has a team of three that works on noise and health; is that correct? That seems extraordinarily small.

Professor Anna Hansell: It is expanding. I think it is going up to five!

Lord Krebs: As you say, there is no statutory advisory committee, as there is for many other environmental pollution effects on health.

Q10 Lord Mitchell: As a supplementary question to that, can we take a look internationally? Have other countries put in place a policy response to these guidelines that we could learn from? Are there any specific interventions you think should be implemented to reduce exposure to the health hazards of environmental noise? Are there any particular settings where the problem is most acute?

Dr Antonio Torija Martínez: My colleague, Charlotte Clark, could probably talk more about international interventions. I will start with the second part of your question. In terms of interventions, if we focus on aircraft noise, there are certainly things we can do. As I said, we are in the process of the modernisation of aerospace and we have collaborated recently with an airport in London. We found that bringing in communities as early as possible in the decision process is very appropriate. It is important to embed communities’ views when planning flight tracks.

The other thing to take into account is that we have the technology these days in aviation to send the aircraft very accurately to the areas we want to. It is not like in the past, when we were restricted with our technology and were unable to reduce the number of people who were exposed to aircraft noise. We can certainly use navigation-based technology to define and optimise flight tracks and minimise the number of people exposed to aircraft noise. Those are probably the things we can do so far.

Professor Charlotte Clark: Has anybody been brave enough to have policy to address it? Not that I am aware of. It is a question that is often asked.

One thing that has had quite a big influence is the European environmental noise directive, which governs noise mapping in cities or towns with populations above 200,000 people. We do that; it is managed by Defra. If we were still in Europe, since WHO those maps must plot the annoyance, sleep and I think cardiovascular—I will check for you. Three health outcomes are now required as reporting under that. I feel that is a step forward.

Lord Mitchell: That would be helpful.

Professor Charlotte Clark: It uses the WHO exposure-response function, so it goes down to those lower levels as well. That is quite a development being done now across Europe.

I am not aware of any policy. I will have a further look into it, but I have not heard as yet of policy. To some extent that might be because the levels are extremely challenging to get to in the real world; I think Antonio would agree. They are low levels to protect health, but there is not an easy fix and it would take several interventions. Even if you got near them, one intervention is not going to get you down to those levels.

Professor Anna Hansell: A comment on interventions: a systematic review of interventions was carried out as part of the WHO guidelines. The key finding was that relatively few studies have specifically looked at interventions. One of the drawbacks of some of the studies on interventions is they look only after the intervention, rather than before and after, which is quite extraordinary.

I am not aware of general policy responses to the guidelines. I am a public health doctor by background, and I would say that reduction at source is the best approach, where you can. There are attempts to reduce noise at source around airports; I have worked with data from Heathrow, for example. We published a paper in 2013 looking at noise levels from 2001-05. We are now updating our study on that, looking at 2006-15, and it is quite noticeable how the noise footprint has reduced over time. There is awareness of it, but there could perhaps be a lot more in other sectors for transport noise particularly.

The Chair: Do building regulations incorporate noise insulation in their requirements?

Dr Antonio Torija Martínez: Yes.

The Chair: Do we think those are adequate? Do they vary? Can councils in different locations insist on higher levels of noise insulation?

Dr Antonio Torija Martínez: The requirements for sound insulation are good. They are fit for purpose for existing sources; I am going to talk about that later. There might be some issues with other new sources but so far I think they are good.

Lord Krebs: If I may very quickly follow on from a comment that Charlotte just made about the European Union having some requirement for mapping of sound: could you expand on that? Until the end of this year we are, through translation of EU law into UK law, still operating under EU rules. Why are we not doing this?

Professor Charlotte Clark: Sorry, I was not clear. We have always done the noise mapping. I think we are on the third round now. It is done every five years, so currently Defra is undertaking the next round. We still report on the environmental noise directive.

My understanding is that a new piece of legislation came in after we had left Europe. That is the bit that covers these health outcomes, but I will ensure that my written evidence clearly sets out where that is. We do still do the mapping, but we do not have this extra bit that has been bolted on since we left.

Q11 Viscount Hanworth: I think my designated question has already been raised and to some extent answered, in so far as we are aware that this is a multifactorial analysis that we are involved in.

One of the other problems with epidemiological studies of environmental nuisances is the difficulty in disentangling the effects of the various causal factors when these factors are highly correlated. There is also a problem with the methodology of a typical regression analysis, which adopts a model in which the causal factors are mutually independent and have linear and additive effects. We know that some of the factors are interactive and their effects are non-linear, and often threshold mechanisms are involved.

My question is: how is it proposed to deal with these complexities in a manner that is perhaps better than has been adopted hitherto? I should add that we are very conscious that these environmental nuisances impact predominantly on people in deprived circumstances. I am distressed to hear that there is insufficient evidence to substantiate this.

Professor Anna Hansell: There is quite a lot in your question. The first question is: can we rely on epidemiological evidence? That is one of the key factors. No epidemiologist would say, “Just rely on my single study.” You must have a range of studies with a range of methodologies, and you carefully assess what the causality is. There are criteria to assess causality—the Bradford Hill criteria—that you would look at. I will make sure I put that in my written evidence.

Key aspects of this are the consistency of studies: if you have several epidemiological studies, are they showing consistent findings? If you do a systematic review, you do a quantitative synthesis and combine the estimates from several studies. You look at coherence. If you see the effects on admissions for heart disease, do you also see noise having an impact on intermediate markers, such as blood pressure or biomarkers? You want to know if the exposure precedes the outcome, so there is a lot of emphasis now on good-quality cohort studies, so you look at the noise exposure and then you follow up with healthy people to see if they develop the disease. That is quite influential.

You look carefully at all the confounding factors—factors that might be associated with both the exposure and the outcome. You want them out of the way; they are nuisances. You need to make sure that there is an association and look at how high that correlation is. You can look at that in your epidemiological analyses. There are different ways of tackling it: you can make a single adjustment in a regression analysis. There are other techniques: there is a principal components analysis, for example, and you can collect them together. I will cite a paper where that was looked at as an alternative way to look at very highly correlated factors and try to disentangle them.

There are other statistical techniques that you can try to look at that influence. You would want to look at biological plausibility—is this a biologically plausible association? Is there some experimental evidence? You would not look just at whether there was an association in this epidemiological study; you would also want to look at some of the experimental evidence. I have cited some of those studies that looked at taking blood pressure measurements at night, or playing noise to people overnight and then assessing their cardiovascular function in the morning. You take all of those together when trying to make an assessment.

This issue of correlation and correlative factors is important. It is something that you need to think about carefully. A lot of epidemiological studies now when they start will draw up a directed acyclic graph—a DAG. You put a diagram together of what you think all the important relationships are and ensure you have accounted for those in your modelling.

Viscount Hanworth: The burden of my question—if it is a question, not a criticism—was that your linear regression model and your principal components analysis in particular are most inappropriate when you have interacting factors. The principal components analysis, which essentially was what was involved in the methodology of IQ testing, postulates hidden components that have no names but are just statistical artefacts. This is an abuse of scientific methodology, as far as I am concerned. That is a very strong statement, but we have considerable disquiet about the cogency of the mathematical methods involved in these analyses. I do not know if you react to that aspersion.

Professor Anna Hansell: It is very fair to start talking about the statistical mechanisms. I must say that the field—

Viscount Hanworth: Not mechanisms, methods.

Professor Anna Hansell: Sorry, I am getting too excited! - the statistical analysis and statistical methods. You are right that we have relied more on the standard techniques in noise research so far, but it is less developed than, say, air pollution. With air pollution, we tend to use much more complex models than we do in noise so far, because there are relatively few studies. It is not as well developed; there are handfuls of studies on noise, compared with the thousands of studies on air pollution and evolution. I would argue that, given the weight of evidence from a number of sources, I do not think you can say that there is no association there. You can look at interactions, and you can put an interaction term in your model, so you put an interaction term as well as your adjustment for a confounder within your model. That is straightforward to do.

Viscount Hanworth: Professor Martínez, maybe threshold effects and non-linearities—can you address that particular question?

Dr Antonio Torija Martínez: As far as I understand it, much of the evidence, as Professor Hansell said, focuses on linear relationships. The problem we have is that we do not have enough studies to build on more sophisticated and complex relationships. In some studies, such as the SoNA 2014 study, the authors implemented logistic regressions, assuming there is a threshold of annoyance [6], but we probably need many more studies and much more data to make it possible to build more evidence that is accounting for potential non-linearities in the relationships between acoustics and health and wellbeing factors.

Professor Anna Hansell: We also look at categorical associations. We are looking not just at the linear. There is some suggestion in the Heathrow analyses that I have done, for example, that there are higher effects at higher noise levels. That is interesting. One of the problems that we have is that the noise data that are available to us are often truncated at 45 decibels or 50 decibels, so we cannot look at what the shape of the exposure-response function is across the whole of the exposure range. That is a real problem.

The other issue that we have is thinking about the models that we are using and how good they are at the low levels, and about the other types of noise that might be around. If you are in a city, for example, you probably have a background noise level of 50 decibels to 55 decibels, and then you have the aircraft noise that you are trying to disentangle from that. It is easier to disentangle and distinguish it if you have 63 decibels of aircraft noise over your house than if you have 53 decibels of noise. There is a problem with the data that we have, in that we cannot do everything that we would like to do statistically because we do not necessarily have the full exposure range.

Viscount Hanworth: Yes, and ultimately you have to incorporate a physiological model as well. Charlotte Clark, can you contribute to this? I realise I am being a bit of a bovver boy.

Professor Charlotte Clark: I am not sure I can add a lot more. We do check the data; we do not just chuck everything in a linear regression. I do not know that I can add more than Anna. The problem of low exposures is an issue. Some of our government departments will not model noise below 50 decibels. Modelling has improved. There are uncertainties in modelling below 50 decibels that Antonio can tell us about, but we are starting to try to do this.

One anecdote is the SoNA study in 2014, which went down to only 51 decibels in a 16-hour metric, but then policy was set at that. The policy for aviation was then set at 51 decibels, and, of course, communities are saying that they do not know if that is where effects begin, because we have not looked at them. I will not get into the logistic/linear debate, but it is very important that we try to model noise across our whole population, because if we are going to have guidance and set thresholds for policy we need to know where effects begin. The Noise Policy Statement for England is very focused on where effects begin. From an epidemiology point of view it is very difficult to use the data to say, “That should be the level”.

The Chair: It sounds as though you are doing an awful lot to cope with small quantities of data. There have been some very convincing arguments.

Q12 Lord Borwick: I should first make a declaration of interest, as I am a trustee of a charity called the Ewing Foundation for deaf children. There is a mess of subjective points here and we are trying to get some sort of objective answer to it. Is the life expectancy of deaf people relevant to this? If they are profoundly deaf and are not affected by noise, do they live longer?

Professor Anna Hansell: The answer is that I do not know. I have not researched specifically in that area, but I think the first thing to know is how deaf people respond to noise. There is the physical sensation of noise that is separate from the acoustic mechanism.

Lord Borwick: Indeed, and degrees of deafness, of course, and at different frequencies and a whole mess of other complexities.

Professor Anna Hansell: The frequencies are also interesting. I think it is fair to say that it has not been adequately looked at in the epidemiological literature. It is something that we can look at in some of the large studies that we have. In my group’s current analysis on the UK Biobank study, which is a very large cohort, there is information on deafness. We would be able to look at that in terms of relationship to noise exposure and outcomes. I am not sure I can answer your question, but it is very interesting, because it relates to several aspects of how noise might affect health.

Lord Borwick: Yes. If we posit that noise and annoyance are bad for health and it turns out that deaf people live longer than hearing people—which I do not think is true, but I do not know; there may be other factors—that would be a completely objective proof, would it not, that annoying noise is bad for human beings?

Professor Anna Hansell: There are different biological mechanisms. You would also need to look at what the biological response was to a noise if it was sensed rather than heard: do your heart rate and blood pressure go up when there is a loud noise, even if you cannot hear it through the acoustic system?

Lord Borwick: Do you know of any research that has been done?

Professor Anna Hansell: I do not, but it is not my specific field.

Dr Antonio Torija Martínez: I have not done anything like that, but thinking about it now, I assume that there will not be sound coming through the auditory system but some exposure to that acoustic energy, probably some vibration in the ears and the body. It might be a different response. Again, I have not done any research in that area, but when you are exposed to acoustic energy it is not just the sound coming through your auditory system; your whole body might be affected. There might be some vibration transmitted through your body and there might be other physiological mechanisms acting there. It is not my area of expertise.

Baroness Northover: Given that one of the things that you are saying is that it may be a small effect, you may have many, much larger effects from being a deaf person, which would neutralise that small effect.

Professor Charlotte Clark: I was going to say similar. There is the whole social isolation, which is a huge predictor of your life expectancy and those psychosocial aspects. It is a really interesting question. I think there would be other things, if you did not find it, that would probably explain why.

Q13 Lord Wei: Looking to the future, we know that there are likely to be changes to sources of environmental noise, such as from the electrification of transport systems. Are there any major possible changes to the environmental and noise exposure landscape that are imminent, and are there any policy implications for these?

Dr Antonio Torija Martínez: Thank you for your question. As I was saying before, we are probably about to experience a significant change in the soundscape we are exposed to. There is going to be a transition towards electric mobility, both on the ground and in the air. On the ground, there is going to be a transition from low-frequency broadband noise towards more high-pitched sounds coming from electric vehicles.[7] That will be especially important in city centres and urban areas, where the speed of traffic is reduced, probably below 30 mph or 20 mph. In these areas is where we are going to experience more that changes in the soundscape.

In the air, we are likely to have operations of new aerial vehicles more distributed around urban and peri-urban areas. It is quite likely that we are going to have an expansion in Urban Air Mobility. There are already drones under operation. We have plenty of companies running field trials in the UK and across Europe. We also have the Future Flight challenge in the UK, investing a significant amount of money into the development of Urban Air Mobility vehicles and associated technologies. There is agreement that there is significant potential for that to keep or to maintain the UK as a leader in aviation.

All these new sources are completely different from what we have now. The evidence for road traffic is linked to the particular characteristics of the vehicles operating with internal combustion engines. If we have different vehicles, or a different traffic composition, you will need to gather new evidence to understand what the noise annoyance will be as a consequence of being exposed to road traffic noise.

In the air, drones and Urban Air Mobility vehicles are completely different from conventional aircraft or helicopters. They have more tonal content, more discrete or pure tones. They have also more high-frequency noise, and they are going to operate quite close to communities. All of that is potentially going to create a significant problem of environmental noise.

We are going to need new evidence and new models. Going back to when I started with the first question, we are going to need models to understand how the sound is generated in these novel vehicles. We are going to need models to understand how people will respond to these new sound sources.

So far, we have some regulation in Europe. For example, we have some regulation for electric vehicles to produce an alarm or alert sound for pedestrians to make them aware that they are approaching, but we do not have any model so far to understand what the contribution of this new fleet of electric cars will be to strategic noise maps. We are going to need to develop models for that.

In the air, we are going to need regulations setting noise limits for these new drones and Urban Air Mobility vehicles. So far, we have some regulation in Europe and some regulation published by NASA on how to measure the noise of these vehicles, but after measuring the noise of these new vehicles we are going to need limits and recommendations, as we have for aircraft, rail and road traffic noise in the WHO. We are going to need to continue to research and we are going to need funding in the UK to develop that evidence on human response to drone and Urban Air Mobility noise.

Lord Wei: Obviously what you are saying is that the data are still being collected, but does it not intuitively make sense that the electric vehicles on the ground might be less annoying or loud, but the drones might be louder? What does the early research say about the disturbances that these cause?

Dr Antonio Torija Martínez: I will focus on the ground first, where we have two situations. In the case of lower speed, you are replacing engine noise with no noise: you do not have any engine noise in an electric vehicle. At the same time, you are going to produce some high-pitched noise coming from the powertrain of electric cars, but also from AVAS. It will be very quiet, but we are very sensitive to that high frequency, and we need to think about not just one single vehicle but hundreds of these vehicles in an area.

Another thing is that, with today’s technology and the power density in batteries, it is quite likely that these vehicles will be slightly heavier than internal combustion engine vehicles. When you have these vehicles operating at higher speeds—over 30 mph, for example—rolling noise, the noise produced by the contact of the tyre with the road, is dominant. If you have a heavier vehicle you are going to have higher rolling noise.

So it is not simple. There have been some studies in the Netherlands suggesting that there will be an overall decrease of a maximum of 4 decibels if you transition from internal combustion engine cars to an all-electric fleet, but those 4 decibels might not be a lot. Again, you have a shift to those higher frequencies that might lead to more annoyance scenarios.

Lord Wei: And what about drones, if they are close to houses?

Dr Antonio Torija Martínez: It is completely different for drones. They are going to produce a high-pitched, tonal, very noticeable noise. I did a study a few years ago where I basically took a drone measurement and simulated different scenarios with that drone operating at different distances from road traffic. Even when we put that drone in a noisy location where you have a lot of road traffic noise, that high frequency was still detected and created some annoyance. In our study we found that, when you have a drone operating in scenarios where there is varying road traffic noise, the annoyance was reported as similar in all of them [8], about seven out of 10.

Professor Anna Hansell: I will bring up unintended consequences. Heat pumps can be noisy, as can mechanical ventilation in houses that have been insulated. I do not think that has been looked at in enough detail yet. One of my colleagues installed a heat pump and it was so noisy that he had it taken out again. That has put me off thinking about heat pumps, until the technology has improved. I think it depends on what type of heat pump you buy, but I do not think that is very widely known. I have also heard that mechanical ventilation can be difficult to switch on and off if it is in your house but not under your control.

Those things need thinking about. I am sure there are good solutions to them, but it is something that we need to think about in the changing soundscape, as well as electric cars and drones.

Lord Borwick: With the increase in traffic congestion in big cities, which seems to be worldwide, it feels as though emergency vehicles are using their sirens far more than they were, say, 20 years ago. I do not know whether that is a valid point or entirely subjective, but sirens are designed to be annoying and noticeable. Is there a conflict between the science of those people trying to make sirens more noticeable and everybody else trying not to be annoyed by them?

Professor Anna Hansell: I wish we had data from monitoring so we could look in more detail at whether it has increased. I think that they are set at a volume to cover someone in a very noisy car who has their music at full volume. It is particularly difficult if you are in a built-up area. I do not know whether it has increased or not because we do not have the data. I could not readily tell you what the impacts on health are, but it is quite noticeable.

Baroness Northover: I want to come in on heat pumps, because I have just come off the Environment and Climate Change Select Committee and we did a report on heat pumps. I want to point you in that direction. Noise was one of the things we looked at, and it seems that it has improved enormously in the manufacture of heat pumps. We made a site visit to where they are made and you could barely detect them. That is obviously a challenge that was recognised and is being addressed.

Dr Antonio Torija Martínez: We have a research project that will run for two years, focusing on air source heat pump noise. I agree with you that there will be a significant improvement in the technology. Anna mentioned earlier that the best intervention is to reduce noise at source. There are two problems with that. First, the way that an air source heat pump is installed and commissioned will have a significant effect on the final noise produced. Also, once you have a machine rotating to move air, as in an air source heat pump, performance will decrease over the years, so there will likely be an increase in noise.

Secondly, from a regulatory point of view, it will be difficult to meet current regulation limits. Imagine you install several air source heat pumps in a very quiet location; it will be difficult to meet the target of 42 decibels in the most exposed façade. These are regulatory issues that should be addressed and we hope to get some evidence to that point.

Baroness Northover: You may wish to look at that report, If your concerns are sustained in the way that you say, feed it in to the Select Committee, because it will get the Government’s reaction to that report and how that is best taken forward.

Q14 Viscount Hanworth: Can anyone say something about the physiological and neurological damage in the auditory system occasioned by exposure to excessive noise? Beyond that, is there any evidence that people who have had their hearing damaged are somewhat less sensitive to nuisances than others who have full auditory faculties?

Professor Anna Hansell: I am not sure.

Professor Charlotte Clark: I am not sure. We would probably have to look at that, but there is a lot of work starting on what is called aural diversity. Neurological or hearing problems mean that you might be more sensitive to certain types of noise, but I do not think there is straightforward evidence that that is the case. Anna and I will be happy to look into that further for you.

Viscount Hanworth: Professor Martínez, does the damage correlate with the power or the energy of the source, or is it something else?

Dr Antonio Torija Martínez: Again, I do not have any evidence there so I cannot provide a certain answer.

Viscount Hanworth: It would be helpful if these things could be tied down because that would give us a clue.

Professor Anna Hansell: There are quite clear occupational limits. Auditory damage is very much tied to decibel levels. You can predict the level of damage according to the decibel level.

Viscount Hanworth: Which is indeed a logarithmic measure of the energy.

Professor Anna Hansell: Which is a logarithmic measure, yes.

Professor Charlotte Clark: You get temporary threshold shifts as well. There is a lot around that. After going to music events, you may get the ringing in your ear the next day. If you have a lot of them, they can cause permanent damage to your hearing.

Viscount Hanworth: Is it mainly neurological?

Professor Charlotte Clark: You have damaged the hair cells in your ears.

Viscount Hanworth: So it is physical damage as well?

Professor Charlotte Clark: Yes, physiological.

Q15 Lord Rees of Ludlow: We have heard in many contexts that more research is needed and we, in writing our report, would like to be able to make some recommendations. In that context, it would be helpful if you could each give us suggestions of where you would like to deploy more effort on research in contexts where the evidence is lacking but which could have a significant policy-relevant impact, if you had the funds.

Professor Charlotte Clark: I have a list; I will not read them all, just the highlights. We do not know about the impact of a range of sources in the UK on outcomes in mental health, well-being and quality of life. They are important for communities, which feel that those outcomes best represent how noise impacts their lives.

We need to quantify interventions: if we insulate your home, how does that change your annoyance response and your cardiovascular response? Does it improve your sleep? Noise insulation in particular is often put forward as the solution, but so is change in noise exposure, as Antonio mentioned. We are undertaking airspace change but we do not have a good understanding of how newly exposing people, or even reducing noise, impacts that.

I have discussed neighbour noise.

My last one is combined noise exposure. You have probably noticed that we tend to treat each noise exposure in its own right. Methodologically, it is a complex area to try to look at exposure to more than one source. However, evidence is coming forward that if you are exposed to more than one source, cardiovascular effects, for example, are much larger if you have two or three exposures.

Professor Anna Hansell: I will start with a comment on the research funding landscape. It has been difficult to get funding for noise and health research. One of the problems is that noise falls between stools. Is it an environmental problem, therefore it’s the NERC research council? Is it a medical problem (this would go to the MRC)? But then they are less interested in the exposure side. Is it a buildings issue (this might to the EPSRC)?

There has been increasing interest in multidisciplinary working in UKRI research funding, but a lot of that has been going towards air pollution. We look enviously at Switzerland, which has had some generous government funding that means it is now world-leading in noise and health research, and in looking at other metrics, and at indoor versus outdoor noise.

What do we need? We are trying to enable some things already, so we are getting noise exposure into large British cohorts. There is a scheme that arose out of Covid-19, the UK Longitudinal Linkage Collaboration [9], which has over 3 million people in cohorts, that data are collected on. Cohorts are groups of people who are followed over time, and health information is collected with their consent. We are putting road transport noise into that.

My group has been enhancing the UK Biobank resource, which involves half a million people, putting in aircraft noise for 100,000 individuals and road noise for all half a million. If the data are there then people will start doing the studies, and we need more general studies to enrich the evidence base.

We need special attention for what are call quasi-experimental studies. If you get changes in noise exposure, it is important to look at that. If you get changes in an aircraft site or an expansion, for example, looking at before-and-after studies can be very useful for inference.

I would support all of the studies that Charlotte talked about. We need to think carefully about the metrics that we use for noise, not just using decibels but thinking about the quality and frequency of the sound. There are issues around people who hear sound differently, which I think we have brought out nicely in the committee. We have also talked about low noise levels and the lack of information on the whole exposure range.

There are a lot of health outcomes one could look at. One thing we have not talked about much today is birth outcomes, for which again there is not much evidence.

Finally, I come back to soundscapes. This is thinking about not just the negative but the positive impacts of sounds. The balance of those is important.

Dr Antonio Torija Martínez: I completely agree with Anna and Charlotte. The first thing to say is that we all recognise the need for engineering the net-zero transition. Usually, noise will be a showstopper; it will be a barrier to the wider adoption of air source heat pumps, electric mobility, drones, etc.

We need funding for addressing those noise issues. In UKRI, acoustics gets funding while connected to other disciplines, but it is difficult to carry out the needed research with acoustics leading those projects. It would be very beneficial if we can have some mechanisms where noise is the driving force of these projects to facilitate the net-zero agenda.

Another thing: at the moment, we are trying to change the way we do things in environmental acoustics, moving from noise control, where we focus only on noise control and decibels, to a more holistic approach called perception-driven engineering. In this approach, we are trying to embed human factors into the design of transport systems, machines and so on. We need some mechanisms to facilitate interdisciplinary research to do this. For example, it is difficult to work within different research councils. You are able to address only one of the issues if you are in the Engineering and Physical Sciences Research Council, the NERC or the Medical Research Council. It will be useful if we have some mechanisms to work at the interface of different research councils because we will take a more holistic approach. Usually, the solution will be interdisciplinary research rather than being constrained by your own research field only.

Lord Rees of Ludlow: I thought that was what UKRI was supposed to do.

Dr Antonio Torija Martínez: There is currently new funding call focusing on this interdisciplinary research, but we will need more in the future.

Lord Rees of Ludlow: It is interesting that it spans many different departments in getting research funding, as well as in implementing any regulations. It has to find someone to take responsibility.

Baroness Northover: You made the point that regulation has moved further forward in the EU. Given the decision, I hope, that we will be able to rejoin Horizon in some way, I wonder whether you see possibilities there. Excuse my ignorance, but I know that Switzerland has opted in for all sorts of parts of the EU. Is Switzerland in the Horizon programme as an associate member or something? If so, is that a route?

Dr Antonio Torija Martínez: I do not think they are.

Professor Charlotte Clark: I do not think so. We are part of some existing EU research on noise and health. Anna and I are both part of a study on the exposome, which looks beyond noise at all environmental, biological and social exposures. That is a £12 million grant from Horizon 2020. It uses a lot of our national cohorts, looking at noise modelled in them. Again, it is focused on child health and children’s learning as well. We can say a bit more about that.

Professor Anna Hansell: The £12 million is across all of the partners.

Professor Charlotte Clark: The £12 million did not come to us. No, that is across Europe. I think that it has about 30 partners. It is a huge project where we all get a few crumbs from the table.

Professor Anna Hansell: These types of projects are incredibly important because we can look across different cohorts in different areas and benefit from a lot of expertise in the area. Not having access to EU research funding stores up long-term problems.

Baroness Neuberger: Switzerland keeps being mentioned. The research in Switzerland has been valuable. Switzerland has very strict rules about neighbour noise and environmental noise. Is that because it has been tracking the effects of noise on health for a long time? Is there a particular research interest that is notably Swiss that we might learn from, or is it just one of those things?

Professor Charlotte Clark: I think that Switzerland was quite late to the research arena in general, so I am not sure that all of its rules are related to that.

Baroness Neuberger: Do you think it is just like that?

Professor Charlotte Clark: I think that it might be a cultural thing.

Baroness Neuberger: I was interested because it has been quite important.

Professor Anna Hansell: It is a large programme of work and a lot has come out of it.

Dr Antonio Torija Martínez: I do not know the why, but in acoustics in general Switzerland produces a lot of useful things. I have no idea why.

Professor Charlotte Clark: Interesting.

Baroness Neuberger: Thank you. It must be cultural. I am interested because I have Swiss cousins; if you have a party after 10 pm you are in real trouble.

The Chair: Let us not speculate on the culture of the Swiss.

Baroness Neuberger: No, I do not think we can do that. I wondered if there was a research link.

The Chair: Interesting thoughts. Thank you so much. I have one final question: Professor Hansell, did you say that according to the noise surveys that things are getting quieter?

Professor Anna Hansell: No, I would not take the interpretation that far, but I would say that aircraft noise has reduced over time in the studies that we have done around Heathrow.

The Chair: Which you would expect as engine technologies have improved.

Professor Anna Hansell: I think Heathrow has worked hard through engagement with communities. It has altered the flight paths. The descent is steeper and there are fines for noisier planes, so it tries to get quieter planes to land at Heathrow.

Professor Charlotte Clark: That time period also covers Chapter 4 planes being phased out, so you would expect a change because the 747s that were very loud have all gone.

The Chair: Do the broader noise surveys that you were talking about that Defra organises tell us that, in general, we are getting noisier or quieter?

Professor Charlotte Clark: They do not often assess noise but they look at attitudes. However, people’s concerns and dissatisfaction have gone up. I will give you a summary in the written evidence on that. People are more concerned about noise than they were 20 years ago. The surveys show that. They do not often have the money to model noise into those surveys, so it is hard to know whether people’s exposure has increased.

Dr Antonio Torija Martínez: One thing we should say is that we have transitioned from fewer, noisier aircraft to more, quieter aircraft; there has been an increase in aircraft operations in recent years.

The Chair: Thank you so much for a very long session. You have answered our questions—whether they were straightforward or not—across a very broad range of areas. We very much appreciate the information you have provided us with; it will be very helpful. Indeed, you have offered to provide us with a range of additional information for which we will be enormously grateful. We look forward to receiving that.

[1] Sound is acoustic energy that travels in waves through air, water, or other substances, and can be heard.

[2] Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average or equilibrium) atmospheric pressure, caused by a sound wave.

[3] This refers to a typical distance between residential properties and a major road or highway.

[4] We need evidence to understand the ‘change effect’ in communities newly exposed to aircraft noise, or, in other words, whether this could lead to higher levels of noise annoyance than would normally be expected.

[5] Carstairs score is a measure of area-level deprivation, derived from Census variables.

[8] Torija et al. (2020) carried out a study investigating the effect of a drone hovering in different soundscapes of an urban area with varying road traffic noise. While at locations with dominant road traffic noise the presence of the drone led to an increase in the reported annoyance 1.3 time the annoyance without the drone; at locations with low road traffic noise, the annoyance due to the presence of the drone increases 6.4 times. In these locations with low traffic noise, the noise annoyance was always about 7 (in a scale from 0 to 10), regardless of the overall A-weighted Energy Equivalent Sound Pressure Level (L_Aeq) in the location.

Torija, A.J., Z. Li, and R.H. Self, Effects of a hovering unmanned aerial vehicle on urban soundscapes perception. Transportation Research Part D: Transport and Environment, 2020. 78: p. 102195. https://doi.org/10.1016/j.trd.2019.11.024.

[9] https://ukllc.ac.uk/. The UK Longitudinal Linkage Collaboration (UK LLC) has been set up to bring together information from longitudinal study volunteers with their routine records. This is being done in a secure way to help researchers work to improve health and wellbeing throughout and beyond the COVID-19 pandemic.