Why listening is so important

Our world is filled with sounds we never hear. The human auditory 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’s 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’s not surprising that modern urban man has turned down 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 recognisable creak, every window a 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 US coins spilled out onto the bare floor. “Three quarters, two dimes, a nickel, and three pennies,” said our host. And, as an afterthought: “One of the quarters is silver.” He was right, to the last penny.

“How did you do it?” we asked. “Try it yourself,” he said. We did, and with a practice, we found it easy. On the way home, we took turns closing our eyes and listening to the sounds of our taxi on the wet street as they bounced off of cars parked along the curb. From that alone we were able to tell small European 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, reported a visit by a blind friend named Justice Fielding. “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, they use 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 non­terrestrial, 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 snail-like 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.”

While we’re still under 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 elasticity. It is unusual for over 50s to hear well above 12,000 CPS. They can still function, of course, since most conversation is carried on within an octave or two of middle C, or about 260 CPS.

Just cutting down reflected sound can produce odd results. The nearest thing on Earth to the silence of outer space is the “anechoic chamber” at the Nokia Bell Labs in New Jersey, which is lined with material that absorbs 99.98 per cent of all reflected sound. People who have remained in the room for more than an hour felt jittery and out of touch with reality.

One remarkable quality 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. Conductor Arturo Toscanini, in 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. Sure enough, a second violinist far back on the stage discovered that he had failed to re­move his mute.

The sound you hear most often 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 conduction. This explains why we hardly recognise a recording of our speech. Many of the low-frequency tones that seem to give our voices resonance and power are conducted to our ears through the skull; in a recording, they’re missing, so our voices seem thin and weak.

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