Acoustics, music and architecture

BBC Sounds. Music, radio, podcasts. Hello, I'm Tom Sutcliffe and this is Start the Week from BBC Radio 4. I hope you enjoy the programme.

It used to be said of the Royal Albert Hall that however terrible a piece of music was, the composer could always be sure of hearing it played twice. The echo in the building was notorious and it took much trial and error by acoustic experts until it could... be improved that's what we're talking about today how sound and buildings interact a subject which brings together science and art passionate subjectivity and a surprising amount of gunfire

With us to do it are Fiona Smith, whose book Pistols in St Paul's traces the development of acoustics from the preserve of a few dedicated enthusiasts to a finely calibrated science. Trevor Cox, Professor of Acoustic Engineering at the University of Salford, who currently holds the record for the longest duration echo ever recorded. More of that in just a moment.

And experiencing acoustics from the all-important performer's perspective, the saxophonist Jess Gillam. She's got concerts coming up in the Symphony Hall in Birmingham and in the Royal Albert Hall, I think, this week. highly regarded as excellent. The other is still a bit challenging, the Royal Albert Hall? Maybe a little. OK, well, we'll talk about it a bit more later. Trevor Cox, I want to come to you first, though.

A few years ago, you wrote a book called Sonic Wonderland, and in that you visited kind of... acoustic anomalies around the world. And one of the places you went to was the Hamilton Mausoleum, which was reputed to have the longest echo in the world. It was sort of 15 seconds or something. You have beaten that.

By some distance. Oh, thoroughly beaten it, yes. Tell us about it. Well, yeah, it was actually, we went to an acoustic conference in Glasgow, and what do you do at an acoustic conference at the Academps Gotham? go to somewhere interesting. In this case, it was the mausoleum. And we sat around and go, well...

It's quite reverberant, but actually probably St Paul's Cathedral isn't very different. And that got me thinking, well, where else might be more reverberant? And you basically start looking for really enormous spaces with really hard construction, no windows or anything. And I ended up in an... oil tank in Scotland. This was a Second World War oil tank, built underground, huge space.

Very often acoustic experts use a starting pistol, don't they? It's a good sharp noise. We can hear that noise now of you shooting the pistol off. I don't know how long we're going to wait. You can hear that reverberating away.

It went for how many seconds in the end? Well, the recording is about a minute and a half long, and actually I stopped it, and it was still going, but it was below where I could hear it. And it is a vast cavernous space, and it was there for shipping oil, and it was by burying it inside a hill. It's sure it wasn't going to get bombed during the Second World War, so it could feed the Royal Navy. But because it is...

It's got incredibly thick walls. It's obviously got nothing else to absorb sound in there. And so the sound just keeps bouncing around. It's the most amazing space to go into. Is the analogy with mirrors...

a reasonable one that you know as it were the shinier and more reflective the surface is the longer the echo is going to last yeah essentially what if you if you're in a room like we're in this studio here we've got lots of fluffy stuff around us to sort of absorb sound you know we've got minimal wool on

the walls we can literally see it because the panelling has come away in one place and we can see the sound absorption in this studio yeah yeah and when jess is playing the concert hall you know it's the audience it's the seating is the main form of absorbent and everything else is made as hard as possible to keep it the sound bouncing around for

as long as possible. Yeah. I mean, you play the saxophone. You also went into this space and played the saxophone. Let's just hear a little bit of that because that creates a very strange effect. Now, there, you're playing with yourself several times over.

by the end of that, aren't you? Yeah, you can have great fun playing chords in there because you play an arpeggio and then suddenly it builds up the chord because the record is for 75 seconds. So you play the saxophone in there, about a minute the sound's going to last. So you have to really think about...

what you play i mean that that piece of bark is kind of a nice piece to play because you've got those pauses to play with the reverberation and you know you either do something like that or you end up playing like whale song very slow moving stuff which can work with very very long reverberation Which, I mean, presumably, Jess Gillum, presumably occasionally...

you get unwanted effects with reverberation that you have to, as a performer, take into account. Yes, if you have a really long reverberation time, if you've played any note slightly out of tune, then you have to adjust the ones that come after.

you are experiencing the harmony, the chord sounds just right. So you're constantly working with the reverb and the sound, but that sounds incredible. It's like the movement in the sound as well. You don't just get the reverb, but this idea that it keeps on circling and moving, it's incredible.

You've got saxophonist's envy now, have you? It looks pretty difficult to get into that space. It's never going to be a performing space, is it? No, musicians do go into it, and there are now regular trips into there. You have to go down a pipe to get into it.

Access for them when they were servicing it was down a pipe which was about 18 inches, about shoulder width across, and it's about a couple of metres long, so you actually get shoved down this pipe. Yes, it looks as though you're being put into an MRI scanner or something. People can see it on YouTube if they want to hear. more of that. Is echo the right word? I saw somewhere that...

If we use the word echo, we're using the wrong word. Why is that? Yeah, it was rather frustrating because there was a record for the echo. Guinness gave me the record for the echo, even though I said, no, what we have is reverberation here. And what's the difference?

acoustics point of view echo is when you hear something distinct and separate you get echo echo it's the sort of thing if you're on a stage of a console which is very deep and there's a reflection off the back and like the Albert Hall you talked about you hear everything twice whereas reverberation is the

bloom you get which you typically if you went to a cathedral you would hear where the sound is enhanced but you're not hearing the notes twice you're just hearing the notes sustained in the space yeah so in the royal albert hall the echo was a real problem you know the joke was you you got a second concert a bar later in the ceiling.

because there was so much echo from that. And it was very distinct, I think. Yeah, and hence why those, in the late 60s, they put the mushrooms in to try and stop the sound going up into the big dome. So the problem with it is it's got a big, focusing dome, which is... a long way away, so the sound takes a long time to go up, it gets focused down, and therefore you hear everything twice. And presumably there are points in the Royal Albert Hall where you're absolutely at the focal point.

And you hear extraordinary things. Is that what is happening in the Whispering Gallery in St Paul's? Is that an echo or a reverberation or just transmitted sound? I don't think you'd call it either, really. I mean, what happens in the Whispering Gallery is you go up, you're inside the dome. It's about 30 metres across and you whisper into the wall on one side and your friend...

Across on the other side, here's the sound coming out of the wall. But what's really happening is it's skimming around the edge of the wall rather than going across the middle of the gallery. I mean, for people who've never been, you hear it with an uncanny kind of precision. Or you can do, if you do it right. The sound is transmitted.

with very little loss very little energy loss as it goes around the inside the dome surprisingly so so you get this sort of whispering gallery effect it's neither you know it's not echoing reverberation about reflections yes there's reflections but you wouldn't use that term yeah okay um We want to turn back the clock and go back to the point at which...

Trevor's job didn't exist at all. You've written this book, Pistols in St Paul's, and it begins with this statement, buildings are in fact instruments of music. I don't think that would be contentious at all now. We've just heard that effect. When do people begin to realise that fact?

That's a really good question. And I think the 20th century approach to acoustics was characterised by this idea of a building as a musical instrument that really started with the construction of Westminster Cathedral. I mean, we did have analogies to buildings as musical instruments in the history.

of architecture before that but this real sort of examining the interaction of sound and space and looking at it as an interdisciplinary phenomenon I think that really began with the construction of Westminster Cathedral in the early 1900s I don't think they used pistol shots

in Westminster Cathedral. They just played bits of music in there, didn't they, to test what was going to happen in that space? Yes, there were a series of tuning concerts as the building was under construction and they were billed as experiments as well as concerts. So there was still this idea... that a concert or that music was something that was probing it out, probing out the acoustics, getting a sense of how the building responded. The first ones were quite small scale, just choirs.

a small choir of boys at different positions within the cathedral and then moving upwards, up the walls with slightly larger choirs positioned in different places in the galleries, and then ultimately a really large concert in 1902 with a huge audience. I mean, as you said, we're in 1901 and 1902 here, so... There's no tape recorders. No. Is there any instrument beside the human ear that they're using? No, it was entirely tuning a building by ear. And...

One thing I was curious about reading your book, the sudden development of this science, is there, to a degree, some forgotten knowledge here? You quote a music critic at one point sneering at the idea that Palestrina... would have had any knowledge of acoustic science. But Palestrina must have had, as a composer in a sacred space, he must have known what that building was going to do to the music.

that he composed I completely agree the response is visceral you can't miss it and if you're working with music in a particularly reverberant context it's very much there but he also literally must have been composing in order to take advantage of an echo that he knew would come, or a reverberation that he knew would come a certain amount of time later. What about Christopher Wren? I mean, it's called Pistols in St Paul's because they did fire a pistol in St Paul's to test the echo there.

Is there any evidence that Christopher Wren knew that his building was going to have acoustic qualities which he had to somehow take into account? Christopher Wren did write about acoustics in terms of how far the voice travels and he looked at it in terms of dimensions. So that was all he had to go on. It was kind of trial and error for Christopher Wren. You built it and then saw what happened.

Yes. And was there any expertise about... I mean, I seem to remember reading somewhere that some church builders built reverberant space in so that a speaker's voice... would carry further. You can certainly, if you go into churches, you can see design. A good example is a tester which sits above the pulpit, a reflecting surface above the pulpit to project the voice of whoever's reading the sermon out into the...

congregation so you can definitely see design things that people have tried and tested and so there's a sort of learn by sort of trial and error in a sense in a sort of artisan kind of way but that's an ad hoc thing after the building is constructed you think okay

We can't hear them. We're going to have to do something about that. But also, if you found it worked in Church A and you're building Church B, you go, well, we need a tester, don't we? Let's put one in because that's what we kind of need. Fiona Smith, coming back to you. Who really gets the credit for establishing acoustics as a science?

It's usually Wallace Clement Sabine, the physicist in Harvard, who came up with the first formula for reverberation time, which was the first mathematical means of predicting how a building might sound. And what was it that prompted him? Really bad acoustics in a lecture theatre. A lecture theatre for students of art history, actually. And the reverberation time was so bad that the words of the lecturer couldn't be heard. And as students sat, organised alphabetically...

If your surname began with anything after F, you really weren't going to hear a single thing in the lecture. How did that come about? Because they must have known. at that stage, you know, what worked for a lecture hall. And so they built this new lecture hall, but all of a sudden, the acoustics are terrible. They did, and the geometry was modelled on another theatre at Harvard, the Sanders Theatre, which has beautiful acoustics. So they tried to copy that.

And it didn't work at all. Some tiny tweak had changed everything. Trevor Cox. I mean, I suppose it's stating the obvious, but sound is invisible. So, you know, we're talking across in this studio. Do you know how sound is bouncing around in this studio? We can't, you know, we have no way of knowing. We know because of all the science that's being done. The same would be true of the Lecce Theatre of the Day. They don't exactly know how.

how it's behaving beyond maybe thinking about it a bit like light. So we also had some understanding, some grasp, but the actual science was pretty primitive in the time. But that thing of, as it were, setting out consciously to replicate... a theatre that you knew worked well and finding that it doesn't at all. There's more than one variable. They replicated the geometry, they didn't replicate the materials. Ah, that's the critical thing.

And Wallace Clements Herving, when he'd done this, how did he kind of then move on to use this knowledge that he'd got, or the measurements? He used it in the acoustics for the Boston Symphony Hall, and it was published in the States. in a number of architecture and engineering journals, but it was a long time before it crossed the Atlantic. It was 17 years before his formula was published here in an architectural journal. He has a scientific unit named after him, doesn't he?

He does. What's a sabin? They've knocked the E off his end. Well, yeah, what's a sabin? Well, we still use it today. So if you go up to our test chambers where we're testing building products, you know, testing carpets that are going to be put in studio, we'll be measuring using...

Sabine's formula, the absorption of carpets that's still in use today. Have I pronounced it right? Is it a Sabine or a Sabine? I call it Sabine, but I wouldn't bat for you that. And what is a Sabine? One Sabine is a measurement of what? How much energy is absorbed.

compared to how much energy is instant. So if you've got something which is completely absorptive, it has a sabine of 1. If it's completely hard and reflective, like a bit concrete, it has a sabine of 0. But we talk about metres squared nowadays, mostly. OK. And is there any such thing that has a sabine of...

of zero that is completely and totally absorbent of sound? Well, the walls of Inchendan are pretty close to it. Nothing is exactly zero. But the reason Inchendan, that oil tank, has such a long reverberation time is the absorption coefficient, the Sabine rating of the walls is incredible. to be small. So Wallace Clement Savine is doing that in America, but your book is mostly about spaces in England. So how does the science get here, Fiona?

There was a slightly different approach at the same time as Sabine was working on his formula and working very precisely on it with detailed measurements all through the night. He took all his measurements at night so that there was no interruption with noise.

The focus here was slightly different, and acoustics hadn't really featured that much in the national press for a few years before Westminster Cathedral was constructed, but with this huge new cathedral being built in London, it suddenly became a topic of conversation, and music was really what... what really grasped attention so what where the interest was was in how sounded space

interacted together in terms of music and looking at ways of quantifying that and even finding a common language to quantify that because architects and musicians and scientists don't always speak the same language. Words mean different things across disciplines. Well, not just that, but they may also be at odds in what they want from the sound.

That too. And we listen differently as well. Yeah. I mean, Jess, there's a whole kind of subjective element here, isn't there, which has nothing to do with the measurement of... metres squared or reflectivity or savins, it's all about feel. It is, and I think the strangest thing as a performer...

The one thing you can never do is hear the performance of what you're trying to do. So you spend so much time developing your sound, wondering how to interact with the space, interact with the length of reverb, but you can never then go out into the audience.

So you're relying on trustworthy years and relying on musicians who've played there before saying, ah, but from out there it sounds like this. And a lot of imagination, actually, in the sound. There's another... sort of intangible which is architects building a building are largely going to be thinking of volume

in aesthetic terms. What they're interested in is what it looks like and how it works on you that way. So was there ever a tension between the early acoustics experts and the architects? Tremendous tension. I think it was even... Architects were advised in the early 20th century to not let acoustics spoil the beauty. That's a way to win.

A competition, a design competition, was to focus on what it would look like and then pad and coax it after the fact. Yeah, so you knew it might cause a problem, but you just mended it once you got the commission and got the money. Trevor Cox, have you ever encountered this yourself now? Well, yeah, I mean, the problem is, especially with big grand concert halls, if it's wrong, it's actually rather hard to mend. Our standards of how good a concert hall should sound nowadays are pretty high.

What happens when you design a console now is you have some allowance that you know you can tune this bit later on in the same way as they did back in the time that Fiona was writing about.

but you have a limit to what you can do. If you make, for example, the hall too wide and not tall enough and the volume's wrong, it's not very easy to change, is it? No. I wondered whether, as I was reading your book, whether modernism played any part in this, because, you know, you begin your book with Westminster Cathedral, which is, you know, brick built and has apses.

a sort of version of sacred architecture. But if you go to the Royal Festival Hall, you have got enormous amounts of flat, hard, reflective surfaces. You don't have the decoration that you have in a Victorian... music hall. So you've suddenly got a much, much more resonant space, which presumably causes problems. Yes, you do. And there was the development of new materials throughout the 20th century as well, plasters that were much harder.

much more strident sounding in how they reflect. And more polished and polished floors and wood surfaces. I wanted to talk a little bit about the proms because that's a very interesting kind of passage of your book. The proms... start in Queen's Hall, which is kind of just across the road from us here in Langham Place, which is a Victorian sort of music space, very ornate, but that constructed...

As though it was an instrument, I think. Yes, it was. It was built in, well, in allusion to a violin. The walls were timber and offset from the walls and the idea... So the internal lining was timber offset from the structural walls and the idea was that... Held out on batons. Yes, exactly. And the idea was that the building would respond like a violin and in plan it looked like the bell of a trumpet and the idea there was that...

that the music would be. It would flow outwards from the stage. And apparently it worked. You know, it has this almost mythical status in the history of acoustics as a wonderful, truly, truly wonderful concert hall. I mean, it can have mythical status because nobody can go back and check because it was bombed in the Blitz and burned to the ground. Now, very interestingly, they then...

They insisted on keeping the proms as a kind of matter of national morale and moved it to the Royal Albert Hall. There wasn't really a worse place they could have gone, was there? I don't know. Well, it seemed logical at the time. It's just that the Albert Hall was so much bigger and the reverberation time was so much longer. So the acoustic brief from moving the prongs from Queen's Hall to the Albert Hall was really complicated. It was also very experimental and difficult to quantify.

I think The Brief wanted a connection between audience and performer, a sense of scale to be completely altered, hourly altered. They wanted rid of the echo, obviously, but that was the one bit that could be objectively discerned. The echo is there or it's not there. But the qualitative aspects, they were much, much harder to...

to put in play or to even get a consensus on. But also simply the space. I mean, somebody calculated at one point you'd need an orchestra of 200 to properly fill the space, and that just wasn't going to happen. And the reverberation time was more than twice as long as Queen's.

Hall. Yeah. I mean, it's always been a problem in Royal Albert Hall, hasn't it? Or in a kind of an interesting challenge. Let's put it that way. It's a great venue. I think it's important to say that, you know, I've been to...

Albert Hall gigs and really enjoyed them but if you were starting from now and you wanted to make a great classical concert hall you wouldn't try to make it so big you wouldn't have a domed roof because it doesn't work so if you look at all the recent big consoles they're going to be around 2000 seats and that's kind of the limit of what you work with for a typical side classical orchestra

Another interesting issue, though, because one of the things that happens when you go to the Royal Albert Hall is, one, you know it has a history of great performances. The space is sort of remarkable. I mean, if you go to the Musikverein in Vienna, this extraordinary gilded space that you enter, again, with a huge history of musical performance, that's going to... overwhelm isn't it any for most listeners it's going to overwhelm any kind of acoustical defects

It was interesting. I went to a conference in order to talk about acoustics and we went to see a gig at the Royal Albert Hall. And it was interesting. So lots of people came out, all sort of analytical listeners, go, oh, that wasn't very good, was it? The acoustics were all wrong. I said, that was great. I really enjoyed it.

It depends if you're having a night off from acoustics or not, I guess. Do you get to have a night off, or are you like a proofreader reading a novel, always on the lookout for... The misprint. I try and avoid doing that on my nights off. Jess Gillam, what about you? I mean, is it very different to you going to the Royal Albert Hall as a performer and going as just somebody listening? Well, I actually had, we had three Christmas shows in there yesterday.

As soon as you step into that building, you feel the history of the space, the stories, the concerts that have happened in there. And there's such a feeling, I think because of the shape of the space, there's a feeling of true community and together. and i think a lot of the time with a concert with music you're trying to establish this connection between stage and audience and that space really helps that happen with the shape of it and then when you're playing it

you really are working hard to project your sound and get it out there. But there is something that just overrides all of that in the feeling of it. Yeah, but you absolutely have that sense that you have to play at a different level of projection in that space. Yeah. And it's interesting, you spend a lot of time as a musician, you're looking at a score and on there you've got a series of dynamics, a series of volumes to follow. That becomes relative.

every time you step into a new space. So in the rehearsal, the first time you step into the hall, you're trying to sort of gauge, okay, what's a loud dynamic in here? And you might play with the character of something loud, but actually be playing it very quietly. Or you might play...

something very quiet and the opposite. But you're constantly trying to work with the space and give the illusion of something happening, even if that's not possible with the reverb of that. There must be spaces that effectively play along with you. I saw one musician describe...

describing playing in the Musikverein in Vienna and sort of saying the building was part of the instrument I was playing, that he had that sensation. Do you ever get that? I don't know whether you've played the Musikverein, but... No, Wigmore Hall here in London. Which is a very similar space, isn't it? It is, yeah. And when you have that sort of glow and halo around the sound that the reverberation gives and that you feel like somehow you're making music together, it's a feeling...

But I think what's interesting is now we're so used to recordings that are pristine and clean. We're stepping into these spaces knowing what the recording sounds like. When classical music would have first been heard, the only time you would hear it would be... at a house concert or a gathering or in the concert hall. Now, because we've become accustomed to this kind of clarity and cleanliness, I think we have different expectations stepping into a hall. And in fact, when...

when they've done experiments on what people want out of console, they find it splits into two groups. So there's the people who like the reverberation and want to be washed over by this, and there's people who want that CD clarity. So actually when you talk about designing a console nowadays, you have to think...

Not everyone wants the same thing. Yeah, Fiona Smith, there are all sorts of subjective terms come up in your book. Dry, warm, crisp, bright. And they all represent a sort of personal taste in one. Your sound is. They do, and it was very difficult to sort of assign numbers to experience or to use that terminology as design criteria because they're very musical terms, but to translate those into architecture.

and define a brief for what to design based on tone was very, very tricky. One thing that I did find puzzling, we were talking about the music, Varane, and we were talking about, you mentioned the Wigmore Hall. Most of those are what's called shoebox designs, in which the space is sort of roughly two cubes put together, like a shoebox.

And they work terrifically well for acoustics, both of those spaces, without, as it were, acoustic knowledge being fed into them. Why don't people just do that again? Well, one of the problems would be is about if you sat... People as close together in the music variety nowadays in a London hall, they would complain because they're really cramped in. So you've got a big audience, but really tight seating space. So modern seating requirements mean you therefore need a bigger space.

the bigger space the reflections take longer to reach you and therefore you get more design problems to overcome but you can still make great modern consoles yeah The Birmingham Symphony Hall I think I saw described as a shoebox, even though it doesn't immediately look like that, but you're going to be playing there. That is another acoustic I think that is regarded as very...

Do you like playing there? It feels beautiful to play in there. You just, again, you have the feeling of working with the hall. And most of the seats, as with the shoeboxes, are, you know, you're looking at the stage. But an interesting place is the Elphilomone in Hamburg.

where they have a kind of marriage between shoebox, and I think it's called a vineyard, which is where the seats are kind of coming out from the stage. Like the terraces on a vineyard are mounting up on the sides. Exactly, yeah, and it's quite a...

At first, a discombobulated experience as a performer because everything is so clear. So the brass that are at the back of the orchestra, you're hearing them as if they were in the first violins. So orchestras spend so much rehearsal trying to figure out where...

to follow the baton of the conductor and trying to pace their sound in there, it's kind of immediate. I would, as a layman, have assumed that you can always hear the orchestra when you're playing because you kind of have to, but that's... Not always the case. No, you can't always. You're often reliant.

on visuals, on looking, and I can usually hear the first violins, but because I play saxophone, that in itself is quite loud. So as soon as I start playing, I'm having to work to adjust my ears constantly to the space to hear the thing that's needed for the internet.

or whatever it might be. Vienna Smith, one of the early realisations was that human beings are quite an important component here, aren't they? You can test the Westminster Cathedral without anybody in it. But the moment you put a full congregation in there... everything changes because we are absorbent. We are the most absorbent component in an auditorium. The most absorbent? Yes. Trevor's nodding, so... Validation. There are these holes that try and recreate in the rehearsal.

or what it'll be like when it... when it's full. And I think there are things that, I don't know how it works, but there are these things that, there are these absorbers on the seat and it just looks strange to look out. It's an empty hall, but you sort of see these ghostly figures that are meant to be absorbing the sound. Oh, I see, they actually put something in every seat.

But normally what they do is just design the seats so when they're flipped up, the back is absorbent in a similar way to when it's being sat on. It's not entirely... the same but pretty close to it it makes a big difference in terms of just capacity doesn't it that a smaller hall that once you get above a certain number of people you are going to get increasing

problems with absorbing the sound. Yeah, in the end, there's a limit to how loud the orchestra can play, so it's limited to how much power they can put into the room, and then the main absorbent is the audience, so that gives a limit of about a couple of thousand on a... typical classical concert hall. And if you go round a classical concert hall, you will find that all the other surfaces, all the walls, the floors, the ceiling, they might...

They might be made of wood, but it's often wood on concrete to make sure they're reflecting really well. Just before I move on to Jess, who is still human-powered, does amplification just take all of this out of the... if a rock band is playing, they don't have to worry about it to the same degree. A rock band does have to worry about it. So if you go into a typical concert hall, you will find that there will be absorbent that gets brought out for the electrified gigs. Otherwise...

It would just be so boomy, it would be really unpleasant to play in. So all the big concert halls pretty much have these variable absorbents they bring out to make it work for electronic music. Because after all, they've got to work as a business, and that's where they make quite a lot of their money. You don't have amplification normally, I assume. You initially played the saxophone as an outdoor instrument, I think, didn't you? In a carnival band. I did, yeah. And now that must be...

Very different. There's no reverberation. There's no resonance. It's just the instrument. Just the instrument, yeah. And the saxophone was designed originally as an outdoor instrument. For military bands. For military bands, yeah. There was a competition in France.

would be the loudest outdoor instrument and what could travel along long plains and be heard. And Adolf Sachs won. And it has this, that's partially to do with the metal, the kind of brightness of the sound. But learning actually to play outside, we were amplified.

when we moved but learning that as soon as you played your sound it kind of hit this dead stop. You think outside the biggest space in the world there'll be all kinds that the sound can interact with. Usually when you're parading along your kind of sound stops right in front of you. learn to adjust it. And is that a more exacting way of listening to what you're playing? You get no assistance whatsoever from this aura, you know, this warm, cosy, enveloping aura of reverberation.

if I have any big performance or if I want to spend some time really honing in on technique I'll try and find the driest space possible and it kind of amplifies in the other way all of the problems with your technique and you try and OK, this is something that I need to work on. I need to work on Airstream here. And you're sort of giving everything with clarity to your ears. And then it feels great when you step back into a reverberant space. Now, I mean, you also record in studios.

Where, you know, like this studio we're in now, my studio manager, Duncan, he can press a button. I don't know whether he's done it now. Yes, I think he has. And suddenly I am in. Westminster Cathedral he can just do it at the flick of a switch I'm going to take it away now so it doesn't irritate people but that's that all flows out presumably of the acoustic calculations being done through the last century that we now know we can feed it back in.

Do you always have reverb added if you're recording in a studio? It depends. It depends where I've recorded and usually who I'm playing with or what we've played. So I love recording at Rack in North London. There it's an old house, so there's some...

sort of feeling of natural reverb in the living room that's become the studio. The Studio 3 in Abbey Road has a kind of warm feel but usually there's a little bloom that I'll put in one ear on headphones just to hear how it'll sound and then you... can interact with that as you record where did you record the Coventry Carol that was at Rack Studios that was at Rack Studios let us hear a little bit of the Coventry Carol

It's got a beautiful haunting quality, presumably that's partly sort of laid on. It's not just coming from the studio you recorded it in. Yes, we added quite a lot of reverb. The producer I work with, Jonathan Allen, is fantastic. We work together.

look at the emotion of it the the emotion of the sound and you think what kind of space do we want to put this into and sometimes we'll make that decision before going into the studio and pick the studio for the sound we're looking for and sometimes it's after spend a long time kind of listening to everything, tweaking, adding the pre-delay and reverb. And you can choose, like you mentioned, you can choose...

any space you like and these banks of spaces that you can just take your sound into. But it takes quite a lot to just sort of, you play into that when you're in the studio. You know that that's probably where you'll go, have some of that happening in the house. headphones so you can really play into the reverb. Presumably it's easy to take it too far. Very, very easy. Because it's rather tempting, isn't it, as a sound? I mean, something physiologically in us responds to that.

Yeah, and I think thinking about what music was written for, so you're looking at some, if we think of sacred music, that's written for being in that space, in a church, in a cathedral, where we kind of want that feeling of unity so the sound is all around.

Maybe a symphony was written for the concert hall, but if you look at something like that with Coventry Carol, that's to be sung and you'd be used to the feeling of being in a big group of people singing it. So you try and recreate that feeling even though it's a solo instrument.

Trevor Cox. I remember someone describing reverberation as being like ketchup. You can add it to food and in moderation it improves most food. And I think that's, you know, it's a really good illustration because you can also...

you know have too much of it but it's really interesting hearing you talk about this electronic way of adding reverberation because in a sense this is where acoustic designers come around full circle from the sort of stuff you were talking about Fiona about you know designing with the music we now if

you went to acoustic consultants you would find rooms where they would play back to architects what the concert hall is going to sound like because although we have all these wonderful numbers and all these graphs and things architects don't connect with those so therefore we have to do is play it back to them then you can start having a conversation about do you like this hall what if we did this to it so listening has come back very much into the design process

I think as architects we think in shapes and numbers and it's really about what's between those numbers, that overall sense of a space and a shape and what you're hearing. Once it's played back, there's a new clarity. Is there any research into that kind of, what I was talking about, that kind of physiological kind of shiver response to reverberation and just to music?

Yeah, I mean, there have been loads of studies which will look like experimental psychology where you'd have people in specialist rooms with loads of loudspeakers around reproducing the sound of the Berlin Philharmonique or the Musikverein and getting people to respond to them. And nowadays you'd probably be measuring physiological...

response you might have eeg caps on to measure their brain responses how you don't have to just rely on their unreliable subjective responses you can actually see something happening well it's interesting because yeah you get behavioral responses where you ask people what do you think and then you have all their sort of...

They're thinking about what they're saying, but if you want to get them just listening, then measure their physiological response is quite good, whether it's a sweat response or the brain response. But then you've got to interpret them, so it's not quite as easy as it sounds. No, so there isn't a recipe that Jess can take away. for the kind of shiver down the spine moment. No, I don't, but... Dumb. Trevor very interestingly quotes, in an article, quotes...

Simon Rattle on the Royal Festival Hall saying, the will to live slips away in the first half hour of rehearsal. He hates the Royal Festival Hall, doesn't he? I mean, not everybody does. Some people like it. Do you have spaces, you don't have to name them, but do you have spaces you dread playing in?

I dread playing generally in theatres. I mean, they're not designed for music, but when you get into that kind of black box space, you have to work so hard to create an illusion of reverb. So you're kind of, I think about it, and this might be... completely scientifically wrong but I think of what

constantly trying to make a self-acoustic. So you're thinking about the way a note ends. You might shape the vibrato or the shape of the end of a note to give the impression that you're in a bigger space than you are. So you can simulate... A reverberation. I try. For the audience. I don't think it happens, but it's just about the, usually volume and speed of vibrato to give the idea of a sound sort of fading away and giving the idea that it's longer than it is. But it's exhausting.

Now, what is that? I mean, theatres are built for audibility. I mean, that's a crucial factor for a theatre. So why are they so bad for music? I think because they're designed for speech. And to hear speech so clearly, like this studio that's really dry, as soon as you have an instrument there where you want that glow and halo, you've got none of that. Now, I never think of this studio as being dry because I don't have that kind of language for it. What do you mean by dry?

I walk in here and you click, you hear a sound and it stops. It's very dead. No offence to the studio. No, no, that's what it's for. So, you know, you hear us through the microphones instead, I take it. Trevor, just quickly, we're sort of... running out of time here. There must be acoustical research like this must feed into kind of audibility for people who are losing their hearing too.

doesn't it? Yeah, so I work on a project called Cadenza which is about trying to improve the processing of music on hearing aids. So hearing aids are amazing things but they're really mostly designed for speech because that's kind of their primary purpose is how to make speech communication.

work but then when you try and use them for music you run into problems and so it's a big research project trying to improve how music is dealt with on hearing aids and when we were talking before we came on air you're kind of working on a and a hearing aid that will know whether it's in a big hall or a small hall, a hall with a lot of reverberations.

Yeah, modern hearing aids now sense where they are so they can change the processing because what you want if you're in a busy restaurant trying to hear people's voices around a table compared to if you're in a concert hall is different. So actually a lot of them have music modes on them, but the performance of these are mixed. So some people like them and some people prefer to take their hearing aids out. So we're trying to come up with ones which work whatever people want.

This is maybe the solution, Fiona. We'll all take our own personal building into whatever the space is. But we'd lose something, I think, if we weren't hearing directly. Anyway, thank you to all of my guests. Trevor Cox.

Professor of Acoustic Engineering at the University of Salford. Fiona Smith, whose book Pistols in St Paul's Science, Music and Architecture in the 20th Century is out now. And Jess Gillam. She's going to be playing Christmas concerts at the Symphony Hall, as we said, in Birmingham. this week and is also presenting carols at the Royal Albert Hall, I think. Next week, Adam Rutherford with more sound, this time an underwater dawn chorus. But for now, thank you and goodbye.

Thanks for listening to this edition of Start the Week on BBC Radio 4, produced by Katie Hickman. And if you're after more conversations on art, science, history and politics, you can find many, many more on the BBC Sounds website.