The Science of Sound

Hello, this is the Infinite Monkey Cage, and he is Brian Cox. His favourite law is the second law of thermodynamics. I would go so far as to say that it makes him hot, but clearly it doesn't, or at least not for very long. And he's Robinins, and his favourite law was Hookslaw, until he found out he only applies below the elastic limit. Why only below the elastic limit? Yet again, Wikipedia with its information ruins my life. Today we are looking at the physics of sound. As we're discussing sound, we've come to the home of the BBC Philharmonic, here in Sulford, sadly though. We couldn't afford the whole BBC Philharmonic, because I frited the entire BBC Science Budgett away on volcano resistant shoes and Gore-tex. Only you hadn't used the helicopter to get here. I was so looking forward to having a violinist, so we had a wit round, and we got just one! So, please welcome this week's special guest, violinist, Julian Gregory. For regular listeners who might not know, we always have a regular violin, because they haven't had it. We do always have regular violinists, but they normally get cut out from being rubbish. Julian, this is a no-pressure situation. violin for us. Juntie, I like my science, Juntie. (HUMMING) That's enough, that's enough, don't overdo it. (LAUGHTER) In today's show, we'll be seeking scientific answers to questions, such as, "What is the most terrifying noise to human ears?" "And what are the probable evolutionary reasons that we find these sounds disconcerting?" "Sounds such as. " Yeah, it's going to be an amazing science show. "Why would we find the sound of a drill that we normally think of as going into our teeth and creating agony? Why would we find that disconcerting?" We'll be giving you scientific reasons. And why does certain sounds just make us miserable? Yes, we're in software, so we are playing that, aren't companies miserable, unlike you lovely northerners, card. So what is the science of sound? To help us find out, we're joined by a panel of experts in the comedian, because we think comedy helps the average listener comprehend the complex nature of the natural world. Yes, for instance, I only understood the ramifications of the relativistic nature of time, when I went to see Ken Dodd. 3am before the first interval. 3am. Joining us today is Trevor Cox, who is a professor in acoustic engineering. His special interest is the perfect design of rooms for intelligible speech and music, which is why he's banned from Radio One. Professor Chris Plack holds the Ellis-Lewid Jones Chair in Audiology at Mancht University, and he's published over 50 articles in peer-reviewed journals, including the effects of low and high-frequency suppressors on psychophysical estimates of vasila membrane compression and gain, popular one. And. I got enough. available in all good bookshops. And. off-frequency growth of masking effects of mascarid duration in forward masking, further evidence for the influence of the peripheral non-linearity, as if further evidence would require to. LAUGHTER Right there, right. I think we've got enough evidence on the peripheral non-linearity now, mate. Finally, Tom Riggler's worth is a comedian and winner of, so you think, a funny competition in Edinburgh. He was also nominated for the Edinburgh Comedy Award and has also won a Sony, but today is returned to his old stomping ground, the acoustic department of Southwood University, that should be made clear that do not stomp in the acoustic department in may affect the results of some of the experiments. And this is our panel. APPLAUSE Trevo, we're in this room, which has been specifically designed for classical music, the home of the BBC Philharmonic. Is the design of concert halls, would you say, a science? Is it an art? Is it architecture? Is it some kind of mixture of the three? It's probably a mixture, but I think in this room, there's more science in here than probably art, because this is. LAUGHTER Maybe I should rephrase. Even when the orchestra is playing. the design of the hall, there's probably more science than art, because it's specifically designed for recording in. So we're not trying to create a great architectural space for audiences normally. So as you look around this room, you'll see Perspex bent shapes above us reflect as they're specifically there to give reflections down to the orchestra so they can hear themselves. We have all these strange slatted things around the walls, which will, specifically, angle to give reflections to help the orchestra hear each other. So there's a lot of design work gone into making this sound exactly right, and that is a science. Now, why is it. we went off from Toro while back, and found that concert halls were not good for spoken word, quite often. A couple of concert halls we play, particularly if Dara Brion talks very quickly about poorly thought out research into neutrinos in Hollywood movies while swearing going, "Ah, there's pesky neutrinos." If he does that very fast, it appears. In a New York accent, no, all those pesky neutrinos. Of course, because he's doing the voice from the film, you idiot. LAUGHTER So when we found that some people in certain corners of the console, but for spoken word, it was very difficult to pick up all of the swearing. LAUGHTER Most concert halls, which are used for classical music, are designed first to work for the orchestra. So they design it to have this big reverberance, but that's not very good for speech. That actually gets in the way of interdigibility. It makes the words run into each other. So most halls, most interdigent halls, have got designs in there. They've got stuff, fluffy stuff. They bring out literally sort of curtains and all sorts of stuff to try and dampen the space damp, when they have electronic stuff, when they have speech. But there are halls where that isn't done very well, and yeah, it's an unintelligible mush. So I like, there was one console we played. The seats had been specially made to absorb sound, forgetting, of course, that hopefully there will be people sitting in the seats. That's sitting on the sound absorber. Oh, that's quite deliberate, because an orchestra will rehearse in an empty console hall, and they don't want the console hall to be very different when they can't play the concert. And if you go and rehearse in a space with wooden chairs, like a church, it'll sound completely different when the congregation coming and fill up all the pews. So they try and make the acoustic roughly the same, empty, occupied half or whatever it is, it's got to be roughly the same. So if you had an audience that looked like most of the people were quite bony, should you then try and compensate by asking for some people who'd let themselves go a bit? Well, to try and absorb the sound. There was a very good paper from Australia years ago, which looked at the effects of clothing on absorption. So they had the audience in various levels of undress, down to swimming trunks, to see what effect it had on the absorption. And we could find a repeat of that experiment this evening. That's home. You need a degree in acoustics here at Salford. So what does that entail? I mean, is it mathematics, it's a mixture of physics, a mixture of engineering? Well, I'm going back. You don't remember 12 or 13 years? Yes, there's been a lot of time and alcohol between then and now. And I must say as well that I did study under Professor Trevor Cox here. So anything I say which is wrong, it's not strictly my fault. But it's basically incredibly hard mathematics. That's my memory of acoustics. It's really, really hard maths. And it's good because I think that's why music is appealing really to me, because artistically, of course, it's very creative, but it's sort of underpinned by this very solid groundwork of physics and hard math. And that's what I'm really fascinated by, the joining of the tube, which is why these rooms are really interesting, because I know it looks awful. But it sounds so alive. And you can create great art in here, but it's all underpinned by this real bedrock of hard maths. So do you think that means people enjoy, you know, as a mathematician? Well, of course, I enjoy Beethoven a lot more, because I understand it mathematically, whereas those people who can't do the sums will never enjoy this. You get musical snobby, though, don't you? You get jazz, and jazz is even harder, like harmonically and mathematically, to unpick than X-factor, for example. So yes, I think musical snobbs would argue that they understand it more, therefore, enjoy it more. The same way that people might like fine wine, as opposed to Vimto. [LAUGHTER] I mean, some we're going to come back, actually, the mathematical underpinnings of music. Let me ask Chris first. We're talking about sound in this room. And I suppose a physicist sound is very simple to define. It's just a pressure wave going through air. But is there more to it, or is that it? Would that be-- how would you define sound? Well, I think there are two definitions, really. You can either define it in a physical way, which is a pressure variation. It doesn't need to be acting the any-medium at all. Or you can define it as sound as something that we hear. And that goes to the essential question, if a tree falls in a forest for no one there to hear it. That's for a huge bend. Well, no, no, no, it's new definition. If a tree falls in a forest, no one there to hear it, then, according to the physical definition, yeah, there's a sound, because you still get pressure variations. But in terms of the psychological definition, then no, that there wouldn't be a sound, because there's no one there to hear it. So it's got to have a receiver to validate the definition. But the interesting thing is when you have sounds, which aren't actually in the physical world, but you hear them. And for an example, that is, I don't know if anybody here has tinnitus where you have some ringing in your ear. If you listen to lots of people nodding out there, I get it a bit. If you've listened to a lot of loud music in your life, you can often damage the ear a little bit. And that can create these sort of phantom sounds. And there's no physical pressure variations going on, but people still say they hear a sound. I mean, I do find it very weird when you say a thing about when a tree falls. The sound does occur just because we didn't experience, doesn't, to me, that there aren't two separate arguments. But I'm- Ond ydych viruses yn dweud ffais iawn gofo ¿lau i'u agu cy Engine? Ywio 'm Gueireיע Inau' aercas'D i? phant horwn oedd boastwch yn maen nhw o gwysцеftr Mae'n amlwys, mae'n amlwys yn ymwys yn sut, oedd ymwys yn cael oedd hynny. Mae'n amlwys yn ymwys yn ddynad. Mae'n amlwys yn ymwys yn ymwys yn ddynad. Mae'n amlwys yn aesd ymwys yn aesd ymwys yn ddynad. Mae'n amlwys yn ddynad. – am gyddoedd yn bopwnwch i sicrhau GIwnnau sian gywedde llwyd [0.55] ceğim儿 fe i'n eu Melisiau due c樣 sk clin oedd sydd i'rfir i'r nelwer b scaffesisteig kryn trynbar ar codd Socland gwnebu ar fraden angご a'r mesynri credu a'r rhywb, ac waidi meus un iawn cwm yma yn jegd Carg o bobl bod y fydd yo codd a fena mladd y N elim cyfغolau llagofio ni'n profimableighiad. Daul o'n u Sound Design acasında i-hai. Po er drithendiadau pobaroldau ni hollаниroo yr o sinoll package. Dyna siile ond micnd barh överwch. Doeddwn gwleiddiad y nowod k Yellio o hun runtimei? Dou alluza instantlyan midynywod hangun. Si wedi eisiau go пach voam i dyfle mae dawch o hwn? Felly yn dbell hyn Dros7n! Ddim brawch dyw fel hynny. Grotog yn cael ei gwnaw ybynod. Mae'r iawn clwyd yn ymdwl. Mae'r iawn ei ddwl. Mae'r iawn i'r iawn ei ddwl. Ma'r iawn amgy'r iawn am rydym wedi'r iawn a'r iawn. Mae'r iawn am ddwl. Mae'r iawn am ddwl. Mae'r iawn am ddwl. Mae'r iawn am ddwl. Mae'r iawn am yng Nghymnauau, yn iawn am yna. Mae'r iawn am rhanol, mae'r iawn am rhanol, mae'r iawn am rhanol, mae'r iawn am rhanol. Mae'r iawn am rhanol yna. He's Brian and Julian, with where I think it's going to be a number 27 Christmas 8. Abba. Thank you and good night. That's a long story to drive safely.