The Sound Book: The Science of the Sonic Wonders of the World

by Trevor Cox

  While listening curbside was fun as a visitor, imagine if you lived close by. I was actually standing by the second incarnation of the road. The first had been too near houses and, as one resident, Brian Robin, was reported to say, “When you hear it late at night, it will wake you up from a sound sleep. It’s awakened my wife three or four times a night.”28 The music produced by the road must have been particularly annoying. Imagine trying to go to bed each night with a garbled “William Tell Overture” going off every few minutes.

  Many standards and regulations dealing with noise annoyance have stringent criteria for tonal noise—sounds that have distinct notes. While the brain has a remarkable ability to habituate to hisses and rumbles, tonal sounds are harder to ignore. This is why bells have been used as signals through the centuries: the loud ringing is penetrating and hard to ignore.

  On the way down from Big Ben’s belfry, I visited the room that houses the clock mechanism, which has another set of wonderful sounds, including the noisy wind governors, which control how fast the heavy clock weights descend inside the tower. The governors are large vanes that rapidly spin against a ratchet mechanism, sounding like a souped-up, old-style football rattle. Machines have revolutionized what we hear, but to assume that all this noise is bad is an oversimplification. As we will see in the next chapter, some technologies are producing the sonic wonders of the future.

  Future Wonders

  S

  ince the Industrial Revolution, our ears have been bombarded with the sounds and noises of technology and engineering. Much of what we hear nowadays—the rumble of a kettle boiling, the ping announcing a new e-mail, or the loud whine of a vacuum cleaner—is artificial and man-made. These sounds are often an accidental by-product of functionality, but increasingly, manufacturers are deliberately manipulating what a customer hears to improve satisfaction and increase sales.

  When you view a car in a showroom, the first aural impression you get is not the roar of the engine, but the click and clunk of the driver’s door opening and closing as you climb in. About ten years ago, automobile makers realized that the door locks and catches rattled in a tinny way as if they were cheaply constructed. New safety standards had required more hefty side bars in case of accidents, so weight had been removed from other parts of the car to compensate, including from the door catch. Perceptual tests show that people associate well-made products with a bassy sound, maybe because big objects tend to be more powerful and create lower frequencies. To get rid of the tinny sound from the catch, absorbing material was added to the door cavity to attenuate high frequencies, and the locking mechanism was changed so that it closed with a shorter, high-quality clunk.1

  What about electronic devices that naturally make no sound? Often these are designed to impersonate old mechanical devices. Press the button on a digital camera to take a picture, and you will hear a recording from the shutter of an old film camera. On my smart phone, if I punch in a number on the touch-screen keypad, I hear the sound of an old-fashioned push-button telephone. One thing that could radically change our sound world is the move away from gas engines to alternative fuels. There are fears, however, that hybrid and electronic vehicles are too quiet at low speeds, making it hard for pedestrians to hear them coming.

  Companies are experimenting with playing noises from loudspeakers hidden under the hood to alert pedestrians. But what sound should they use? Why, something familiar that immediately makes pedestrians think “vehicle.” Nissan has opted for a hum that you could imagine Luke Skywalker hearing from his hovering transporter on the planet Tatooine. In one scientific experiment, however, people preferred the noise of an internal combustion engine over hisses, hums, and whistles.2 There is a legacy of old sounds surviving from obsolescent technologies. As a correspondent to New Scientist wrote, “Imagine if this concept of familiar sounds had been developed earlier. Would cars all make the sound of horses’ hooves instead of the newfangled and confusing drone of an internal combustion engine?”3

  What is done when there are no old technologies to imitate? Sometimes manufacturers of electronic devices turn to musicians. When composer Brian Eno was asked to write the start-up music for Windows 95, the specification included about 150 adjectives: “The piece of music should be inspirational, sexy, driving, provocative, nostalgic, sentimental, . . .”—a challenging request, especially considering that the musical snippet was to be “not more than 3.8 seconds long.”4

  For brief function sounds, designers might create a click, beep, or buzz. They often start with a recording of something natural and then manipulate it in software. The audio processing might make the end result almost unrecognizable, but starting with the recording of a real sound gives the end result a natural aural complexity that affords it a sense of believability. The “unlock” sound of the iPhone is very similar to the click and spring of a locking pliers opening. Function sounds are best when they fit with the dimensions of the digital device, using frequencies that could plausibly be created from a mechanical object of a similar size. When sounds and functions are properly matched, the electronic object starts to feel mechanical.5

  It makes me uneasy that our aural environment is becoming peppered with sounds primarily designed to sell products. Globalization of technologies also causes an attendant homogenization of the noises that form the backing track to our lives. Although electronic products allow sounds to be changed and customized, a sonic free-for-all is not always a good idea. I remember the cacophony created by personalized ringtones, which are fortunately now less fashionable. I would suggest that “personalization” should be done only en masse, using something that resonates with local culture and history. Maybe electronic cars in Bangkok could re-create the putt-putt of the tuk-tuk rickshaws, and the population of Manchester could change its ringtones to play the clatter of the cotton mills that transformed the city during the Industrial Revolution.

  If I look back a couple of decades from now, some of today’s technical sounds will be nostalgic sonic wonders. I can be sure of this because it has happened before. When I hear the two-tone beeps from Pong, I am reminded of playing that computer game at a friend’s house as a teenager. As we’ve learned from people’s reactions to birdsong, sonic nostalgia will not just be about the most unusual or aesthetically pleasing; it will include everyday sounds associated with strong individual memories. In the future, maybe couples will not just have “our tune” but “our bleep”; they’ll cherish the alert sound as their loved one’s message arrives on Facebook.

  What first drew me to architectural acoustics is the fusion of the objectivity of physics with the subjectivity of perception. Engineers might have sophisticated computer programs to model the physics of sound waves, but that counts for nothing if listeners judge the acoustics to be poor and find what they hear unacceptable. In a grand concert hall, the audience judges whether their enjoyment is enhanced by the room’s acoustic. In a noisy school canteen, the students are annoyed that they cannot easily chat with friends. Scientists have worked out the physiology of this hearing, but we only partially understand how a brain then processes and emotionally responds to sound. Despite this chasm in knowledge, computer models are invaluable, enabling engineers to calculate how many acoustic absorbers are needed to quiet the school canteen or what shape to make a concert hall to enhance the music. Meanwhile, scientists are striving to take the models further and predict what happens between the ears.

  In all the architectural sonic wonders I visited, it was what happened after the initial impulse from a balloon burst, hand clap, or gunshot that distinguished the most remarkable places, especially if it confounded my knowledge of physics. Psychologists and neuroscientists are just starting to unravel how expectation plays a crucial role in our response to sound. A common example is music, in which composers toy with our emotions by subverting what listeners anticipate. Scientists have tested this idea by measuring changes in skin conductance when a note or chord in a piece of music is altered to something surpris
ing. Unexpected notes cause listeners to sweat a little more—physiological evidence of an emotional response.6 Subverted expectation was important to my perception of the gunshot in the oil storage tank at Inchindown (see Chapter 1). I had anticipated a long reverberation time, but I was astonished by the tsunami of sound that enveloped me and took a ludicrously long time to die away. Open a book on architectural acoustics and look at a table of reverberation times in classrooms, concert halls, and cathedrals, and none of them will have values close to what I measured at Inchindown. In this hidden complex, deep within a hillside, I felt like a gentleman explorer from a century ago. There was the claustrophobic entrance to the oily concrete cavern through the tight pipework, the revelation of the awe-inspiring sound, and of course, the feeling of uniqueness: no one had tested acoustics like this before.

  I have discovered that dilapidated buildings, abandoned military installations, and the remnants of industry offer some of the most unusual acoustics. The disused cooling towers of the Thorpe Marsh Power Station in England was the one sonic wonder that eluded me. The station closed in 1994, but the tall, hourglass brick towers were left standing. According to the e-mail correspondent who suggested I should visit the decommissioned power plant, the 100-meter-high (330-foot) towers produced “terrific” echoes inside. Even better, said my correspondent, there was no security, so one could just walk into the site from a neighboring road. One autumn day after I had finished visiting all the other sonic wonders, I packed up my recording gear and drove over to the site. Having been in the radome of Teufelsberg, I could guess the sound effects I might hear in the cooling towers: focused echoes in the center reverberating above my head and whispering-gallery effects around the edge were likely. I took along my saxophone because I thought it would be fun to try and improvise with the echo, and see how that might affect me as a performer.

  But, disaster! All that remained of the towers were some very large piles of rubble. After standing untouched for eighteen years, they had been torn down a month earlier. As I drove away disappointed, I was reminded of the story of the Teatro La Fenice in Venice, one of the best-sounding opera houses in the world. The building burned down in 1996. Fortunately, two months before the fire, binaural recordings of the theater had been made. Binaural measurements use a mannequin with microphones buried in the side of its head to pick up what would normally pass down the ear canals of a listener. Unlike normal stereo, listening back to these types of recordings can give you a real sense of being in a space. The binaural recordings of the Venice opera house helped inform the reconstruction.7

  Efforts to document acoustics have focused on auditoriums, churches, and ancient sites like Stonehenge. Recording the acoustic footprint preserves it for posterity, and makes it possible to bring a place back to life by rendering it in virtual reality. But we should also be preserving the remarkable acoustics of more modern places. There are three radomes on the roof of the disused listening station at Teufelsberg in Berlin, but two of these have been very badly vandalized. Will someone capture the acoustic signature of the last radome before it, too, becomes damaged and the sound is lost forever? Heritage organizations need to realize the importance of sound and not just document sites in words and pictures. There must also be other detritus of human progress harboring sonic wonders waiting to be discovered. And no doubt, new constructions are unwittingly producing the sonic wonders of the future as I write.

  While this book is about finding the most remarkable sounds, I have noticed that keeping an ear out for extraordinary examples has made me enjoy and take more notice of everyday sounds. It was in the Mojave Desert that I first really noticed how evergreen trees whistle. Now, as I walk near my home, I listen for the rustling plane trees lining the streets, and I can even enjoy the wind whistling through that scourge of suburbia, the Leyland cypress. One morning I got up very early to hear bitterns boom because they make the oddest bird call in Britain, and now I listen for snatches of birdsong as I cycle to work dodging between cars. I now appreciate how varied water sounds can be, from the overwhelming roar of the Dettifoss waterfall to the more subtle babbling brook in my local city park.

  There must be other natural sonic wonders waiting to be heard by humans. Every week, new animal species are discovered, and since nearly every one of them hears sound or senses vibration, new animal calls are bound to be revealed. It is a great time for amateur naturalists to seek out and record such sounds. The recording of audio on video cameras or mobile phones is becoming increasingly common. Many of us now carry around technology that can capture sonic wonders and share them with friends and family. New natural behaviors, such as the way one vine has evolved to attract pollinating bats (described in Chapter 3)—new ways that animals and plants exploit sound—will also be discovered.

  At my university, the anechoic chamber wows visitors because the silence allows them to listen to their hearts and minds. I have always thought it would be good to have one in a shopping mall so that more of the public could experience the silence. I think it would also be fun to make one with transparent walls; at least one concert hall has been built with huge glass walls, so why not an anechoic chamber? To do this, the foam wedges that cover every interior surface of a conventional design would have to be replaced with transparent absorbers. There has been a lot of interest in transparent acoustic treatments lately because they fit with the trend in architecture for lots of glazing. They can be made from perforated plastic, a bit like the rustling plastic bags that warm bread used to be sold in. They are not perfect at removing sound, but by curving the walls of a see-through anechoic chamber, like the bottom half of a goldfish bowl, any reflected sound could be directed up above the head of the listeners. In this room you could take a break from the city in complete silence, while others walk by laden with shopping bags.

  For me, the more conventional anechoic chamber at Salford University has become a normal room for scientific experimentation, partly because of my brain’s automatic habituation to the acoustic, but also because I took it for granted. I started collecting sonic wonders because I realized I needed to rediscover the skill of listening. In an effort to awaken my ears, I went on soundwalks, participated in a silent retreat, and floated about in brine. Along the way I have had the chance to interview inspiring artists, sound recordists, and musicians who have demonstrated enviable sensitivity and understanding of the aural. They taught me so much, and made me realize that scientists and engineers need to listen more to them and to the world around us. I hope all of us will open our ears to the strange sounds around us. As my search draws to an end, I realize that I have changed. If we all listened to and cared for the sonic wonders around us, as I now try to do, we would start to build a better-sounding world.

  Acknowledgments

  It has been a privilege to discuss acoustics with many great people over the last twenty-five years. I would like to thank the following, who, for this book, explained acoustic phenomena to me or helped me to gain new sound experiences: Keith Attenborough; Mark Avis; Michael Babcock; Barry Blesser; David Bowen; Stuart Bradley; Andrew Brookes; Angus Carlyle; Mike Caviezel; Dominic Chennell; Rob Connetta; Frances Crow; Marc Crunelle; John Culling; Peter Cusack; Helen Czerski; Peter D’Antonio; Bill Davies; Charles Deenen; Stéphane Douady; John Drever; Bruno Fazenda; Linda Gedemer; Tim Gedemer; Tony Gibbs; Wendy Hasenkamp; Marc Holderied; Diane Hope; Seth Horowitz; Simon Jackson; Brian Katz; Paul Kendrick; Allan Kilpatrick; Tim Leighton; Jane MacGregor; Katherine MacLean; Paul Malpas; Barry Marshall; Henric Mattsson; Bryony McIntyre; Daniel Mennill; Andy Moorhouse; Myron Nettinga; Stuart Nolan; James Pask; Lee Patterson; Chris Plack; Eleanor Ratcliffe; Brian Rife; John Roesch; Duncan from the Royal Society for the Protection of Birds (RSPB); Martin Schaffert; Ann Scibelli; Clare Sefton; Jonathan Sheaffer; Bridget Shield; Matt Stephenson; Davide Tidoni; Rupert Til; Lamberto Tronchin; Rami Tzabar; Nathalie Vriend; Chris Watson; Nick Whitaker; Andrew Whitehouse; Heather Whitney; Pascal Wyse; Luray Caverns; members of Subterranea Britannica; the
teachers, coordinators, fellow retreatants, and staff at the Buddhist retreat; and anyone else I accidentally left off this list.

  I thank the Engineering and Physical Sciences Research Council for my Senior Media Fellowship, which gave me the time to develop the proposal for this book. Also many have helped me to develop as a science communicator, including staff at the BBC Radio Science Unit and New Scientist.

  My agent, editors, and copy editor have been highly influential in shaping the overall narrative of this book and improving the writing. I’m indebted to Stephanie Hiebert, Tom Mayer, Zoë Pagnamenta, Kay Peddle, Peter Tallack, and Gemma Wain.

  Thank you to Nathan Cox, who helped with some of the diagrams. Finally, thanks to the following, who commented on early drafts: Deborah, Jenny, Peter, and Stephen Cox.

  Notes

  Prologue

  1 M. Spring, “Bexley Academy: Qualified Success,” Building, June 12, 2008.

  2 The New Yorker described The Phantom Tollbooth as the “closest thing that American literature has to an ‘Alice in Wonderland.’ ” A. Gopnik, “Broken Kingdom: Fifty Years of the ‘Phantom Tollbooth,’ ” New Yorker, October 17, 2011, http://www.newyorker.com/reporting/2011/10/17/111017fa_fact_gopnik.

  3 British Library Sounds, “Programme II: B—Part 1: Listening. Soundscapes of Canada,” http://sounds.bl.uk/View.aspx?item=027M-W1CDR0001255-0200V0.xml, accessed October 6, 2011.

  4 R. M. Schafer, The Soundscape: Our Sonic Environment and the Tuning of the World (Rochester, VT: Destiny Books, 1994), 208.