In our over­stim­u­lated daily lives, we of­ten shut out as much noise as we can. But when you turn off the sound, you tune out the world

Reader's Digest Asia Pacific - - Contents - JOHN KORD LAGEMANN

Sur­round your­self with sound.

Our world is filled with sounds we never hear. The hu­man au­di­tor y range is lim­ited to be­gin with: if we could hear sounds lower than 20 vi­bra­tions per sec­ond, we would be driven mad by the rum­blings and creak­ings of our mus­cles, in­testines and heart­beats; every step we took would sound like an ex­plo­sion. But even within our au­di­tory range, we select, fo­cus on, and pay at­ten­tion to only a few sounds – and blot out the rest. We are so as­saulted by sound that we con­tin­u­ally ‘turn off’. But in the process, we shut out the glo­ri­ous sym­phony of sound in which the liv­ing world is bathed.

Ev­ery­thing be­comes more real when it’s heard as well as seen. It is, in fact, quite hard to re­ally know a per­son by sight alone, with­out hear­ing their voice. And it is not just the sound of the voice that in­forms. Even the rhythm of foot­steps re­veals age and vari­a­tions of mood – ela­tion, de­pres­sion, anger, joy. The sound-tor­mented city dweller who ha­bit­u­ally turns off their au­dio loses a di­men­sion of so­cial re­al­ity. Some peo­ple, for ex­am­ple, pos­sess the abil­ity to en­ter a crowded room and from the sounds en­coun­tered know im­me­di­ately the mood, pace and di­rec­tion of the group as­sem­bled.

Ev­ery­thing that moves makes a sound, so all sounds are wit­nesses to events. If touch is the most per­sonal of senses, then hear­ing – which is a sort of touch­ing at a dis­tance – is the most so­cial of the senses.

It is also the watch­dog sense. Sounds warn us of hap­pen­ings. Even as we sleep, the brain is alerted by cer­tain key sounds. A mother wakes at the whim­per of her baby. The av­er­age per­son is quickly roused by the sound of his own name.

Watch­dog, stim­u­la­tor, arouser – it is not sur­pris­ing that mod­ern ur­ban man has turned down and even crip­pled this most stress­ful of senses. But hear­ing can also soothe and com­fort. The snap­ping of logs in the fire­place, the gos­sipy whis­per of a broom, the in­quis­i­tive wheeze of a drawer open­ing – all are com­fort­ing sounds. In a well-loved home, every chair pro­duces a dif­fer­ent, recog­nis­able creak, every win­dow a dif­fer­ent click, groan or squeak. The kitchen by it­self is a source of many pleas­ing sounds – the clop-clop of bat­ter stirred in a crock­ery bowl, the chor­tle of sim­mer­ing soup.

Most peo­ple would be sur­prised to dis­cover how much the sense of hear­ing can be cul­ti­vated. At a friend’s house re­cently, my wife opened her purse and some coins spilled out, one af­ter an­other, onto the bare floor. “Three quar­ters, two dimes, a nickel, and three pen­nies,” said our host as he came in from the next room. And, as an af­ter­thought: “One of the quar­ters is sil­ver.” He was right, down to the last penny.

“How did you do it?” we asked. “Try it your­self,” he said. We did, and with a lit­tle prac­tice, we found it easy. On the way home, my wife and I took turns clos­ing our eyes and lis­ten­ing to the sounds of our taxi on the wet street as they bounced off the cars parked along the kerb. From that alone we were able to tell small for­eign cars from larger Amer­i­can cars. Games like this are one of the best ways to open up new realms of hear­ing ex­pe­ri­ence.

An­other ben­e­fit of hon­ing your hear­ing is that ex­tra­sen­sory fac­ulty that blind peo­ple call fa­cial vi­sion. More than 200 years ago, Eras­mus Dar­win, grand­fa­ther of Charles Dar­win, re­ported a visit by a blind friend. “He walked into my room for the first time and, af­ter speak­ing a few words, said, ‘ This room is about 22 feet long, 18 wide, and 12 high’ – all of which he guessed by the ear with great ac­cu­racy.”

Sound en­gi­neers call it am­bi­ence: the im­pres­sion we all get in some de­gree from sound waves bounc­ing off walls, trees, even peo­ple. For a blind per­son to in­ter­pret the echoes ef­fec­tively, he uses a tap­ping cane, prefer­ably with a tip of me­tal, ny­lon, or other sub­stance that pro­duces a dis­tinct, con­sis­tent sound. (Wood doesn’t work, be­cause it cre­ates a dif­fer­ent sound wet than dry.) The me­tal noise­maker called a cricket is equally ef­fec­tive. An­i­mals, both ter­res­trial and non-ter­res­trial, also use ‘echolo­ca­tion’. The bat, for ex­am­ple, emits a very high-pitched sound and picks up echoes from any ob­sta­cle, even as thin as a hu­man hair.

The hu­man ear is an amaz­ing mech­a­nism. Though its in­ner op­er­at­ing parts oc­cupy less than a cu­bic inch, it can dis­tin­guish from 300,000 to 400,000 vari­a­tions of tone and in­ten­sity. The loud­est sound it can tol­er­ate is a tril­lion times more in­tense than the faintest sounds it can pick up – the drop­ping of the prover­bial pin (or, if you pre­fer, the soft thud of fall­ing snowflakes). When the eardrums vi­brate in re­sponse to sound, the tiny pis­ton-like stir­rup bones of the mid­dle ear am­plify the vi­bra­tions. This mo­tion is passed along to the cham­ber of the in­ner ear, which is filled with liq­uid and con­tains some 30,000 tiny hair cells. These fi­bres are made to bend, depend­ing on the fre­quency of the vi­bra­tion – ­shorter strands re­spond to higher wave­lengths, longer strands to lower – and this move­ment is trans­lated into nerve im­pulses and sent to the brain, which then, some­how, ‘hears’.

The hu­man ear can dis­tin­guish from 300,000 to 400,000 vari­a­tions of tone and in­ten­sity

While we are still un­der the age of 20, most of us can hear tones as high as 20,000 cy­cles per sec­ond (CPS), about five times as high as the high­est C on a pi­ano. With age, the in­ner ear loses its elas­tic­ity. It is un­usual for a per­son over 50 to hear well above 12,000 CPS. He can still func­tion, of course, since most con­ver­sa­tion is car­ried on within an oc­tave or two of mid­dle C, or about 260 CPS.

One re­mark­able qual ity of the hu­man ear is its abil­ity to pick out a spe­cific sound or voice from a sur­round­ing wel­ter of sound, and to lo­cate its po­si­tion. The con­duc­tor Ar turo ­Toscanini, re­hears­ing a sym­phony or­ches­tra of al­most 100 mu­si­cians, un­err­ingly sin­gled out the oboist who slurred a phrase. “I hear a mute some­where on one of the sec­ond vi­o­lins,” he said an­other time in stop­ping a re­hearsal. Sure enough, a sec­ond vi­o­lin­ist far back on the stage dis­cov­ered that he had failed to re­move his mute.

We owe our abil­ity to zero in on a par­tic­u­lar sound to the fact that we have two ears. A sound to the right of us reaches the right ear per­haps .0001 sec­ond be­fore it reaches the left. This tiny time lag is un­con­sciously per­ceived and al­lows us to lo­calise the ob­ject in the di­rec­tion of the ear stim­u­lated first. If you turn your head un­til the sound strikes both ears at once, the source is di­rectly ahead. Try it some­time when you hear the dis­tant ap­proach of a car.

The sound you hear most of­ten and with great­est in­ter­est is the sound of your own voice. You hear it not only through air vi­bra­tions that strike your eardrums but also through bone con­duc­tion – vi­bra­tions trans­mit­ted di­rectly to the in­ner ear through your skull. When you chew on a stalk of cel­ery, the loud crunching noise comes mainly through bone con­duct ion. Such bone con­duc­tion ex­plains why we hardly recog­nise a record­ing of our speech. Many of the low-fre­quency tones that seem to us to give our voices res­o­nance and power are con­ducted to our ears through the skull; in a record­ing, they are miss­ing, so our voices of­ten strike us as thin and weak.

Alas, it’s pos­si­ble that hear­ing will at­ro­phy even fur­ther in the fu­ture, as civil­i­sa­tion be­comes busier. When too much is go­ing on, we learn to ­ig­nore most of the sound around us, which means we also miss much in­for­ma­tion and sounds that could give us plea­sure. That’s too bad – be­cause there is a wis­dom in hear­ing.

The sound you hear most of­ten and with great­est in­ter­est is the sound of your own voice

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