Category Archives: Models

Examples we can productively study

Hearing is Our Newest Sense

The pop recording “High the Moon” was the audio equivalent of an early photograph, or the first photocopy of an original. It changed everything. 

Granted, the heading for this piece is a bit of an exaggeration, but not by much.  In broad terms, a bit less than 100 years ago sound arguably became the premier source of leisure and pleasure. Think of radio, recordings, sound on film, concerts and dances, audio reports of events, and the growth of music education. These are just a few of the cultural landmarks represented by the capture of ephemeral sound on the medium of magnetic tape.

To be sure, Thomas Edison starting making stylus-in-groove recordings in the late 1870s.  But the German invention of audio tape during World War II perfected recording, creating  a level of accuracy in musical reproduction that surpassed the early Edison technology.  With tape, sound as we know it began to throw off its previous history as a subordinate sense.  More recent digital recording developed in the 1980s was certainly a technological breakthrough, but offered only slightly better sound. Magnetic tape provided the true gateway to the world of captured auditory content.

The pathway to this rebirth was certainly helped by the growth of what was then the supermax medium of radio in the 1930s. Radio networks and their stations would also benefit from new tape machines made by Ampex and others, adding stunning clarity and opening up a range of recording options.

In the recording studio the new system yielded greater clarity, and allowed for many synchronous tracks. A musician could now create amazing audio effects that would have been difficult to duplicate in live performance.  As mentioned in my recently published The Sonic Imperative, one particular song especially turned jukeboxes across the nation into the musical equivalents of slot machines. The only difference was that most jukeboxes came up with the same winning result: Les Paul and Mary Ford’s How High the Moon. Rarely has a single pop record meant so much. Prior to 1951 few had ever heard anything quite like its sound-on-sound and multi-track effects. It would signal the acceleration of music processing that continues down to the present.

A little more about that song. . .

Our dilemma is that we live in a loud world our ears were not designed for. Think of noise as aural trash: stuff that piles up around us that we hardly notice because it has no visual presence.  But its there: at music concerts where the sound is punishingly loud, or in the everyday equipment of modern life like leaf blowers, hair dryers and vacuums.  Previews shown in movie theaters, for example, regularly play at about 100 dB: only slightly less than standing at the end of an airport runway.  With this kind of noise, a person’s ears will not survive intact to adulthood.  This is why one in three older adults have hearing loss. It turns out that our newest sense is also the most vulnerable.

Remarkable Features of Sound

Because we grow up with our senses mostly intact, we naturally take them for granted. We rarely pause to explore how various receptors make connecting to the world possible.

Details about the sensory equipment we carry are fascinating, none more so than sound and hearing. Their obvious importance rests uncomfortably near their precarious fragility. Exploring this subject in The Sonic Imperative over the last few years was not exactly a vacation, but it was an interesting visit to a different geography that is often overlooked. The journey revealed many surprises, including these three:

  1. The speed of sound is relatively slow. We think of breaking “the sound barrier” as the very definition of “fast.” But in the broader perspective of sound physics, our atmosphere puts a considerable drag on the distances a voice, piano or evening thunder can cover. Sound travels through the air at about 1125 feet a second. That’s about three football fields long, or a little more than the length of the long side of one block in Manhattan. When you watch nearby fireworks, they usually come with a delay between the explosions of color and their sounds; the relative delay is obvious. Lightning gives us an the same sense of the huge gap between the speeds of light and sound. Light travels 186,000 miles in the same second that sound covers a few hundred feet. And here’s the interesting point that is also an advantage to humans and other animals. The relative slowness yields what is sometimes called the “shadow” effect in listening. We have two ears  6 or 7 inches apart. That’s enough to give our binaural hearing a chance to hear the difference in the arrival of sound to one side and then to the other: one reason music in a great hall or on a good system is so pleasing. Even if we can’t see them, we can locate instruments or singers in a dimensional “soundstage.”

2. Another unusual feature of hearing is that sound may be the most persistent of all senses. We never shut our ears as we do with our eyes. And although its unfortunate that adults have usually lost some hearing acuity due to age and abuse of hearing receptors, most of us actually start picking up sounds in the womb at about 30 weeks. We hear our mothers before we are born. Equally unusual, there is some evidence to suggest that hearing and its brain functions survive for a short time even after death is pronounced.

3. Home music listeners have to face hard truths about the limits imposed by a listening room. Most domestic spaces are too small to accurately produce low frequency sound energy: the very source of what gives music so much of its punch and presence. The fact is that low frequency sound “waves” require a lot of energy and are long: often longer than the available space. The sound produced by a nice fat bass note produced on a piano or a bass guitar at 40 Hz unfolds fully only in a space of 28 feet or more. No such problem exists for higher notes in the musical scale, which may have waves which are just a few inches in length.

Why is the lower number a problem? A sound wave that does not have sufficient space for its full cycle will distort, a bit like waves that break against a cliff. We obviously can’t see it, but sound energy that has insufficient space to play out as it should results in what I think of as “wads” of faux bass: a lot of boom but not much musical clarity. Sound engineers often call this undefined low-note energy “one-note base:” an indistinct rumble of low frequency wave energy bouncing off walls or ceilings before it has run its course. To a careful listener the effect is “muddy” or “boomy.” One reason we cherish big old spaces like Paris’ Notre Dame Cathedral is that its 400-foot length is a perfect acoustic for its two organs and singers. To be sure, we have grown tin ears that accept dead thuds of low frequency sound as base.

It can be a revelation to accurately hear low notes as they are meant to be heard. This is one reason audio in a good movie theater or concert hall is usually going to sound better than audio of the same program reproduced in a 20 by 12-foot living room.  One cure is to listen to music at at a moderate listening level, which is usually handled better by a room of limited size.

These and other interesting facets of sound are explored more fully in a host of books, including—a pitch is coming: The Sonic Imperative: Sound in the Age of Screens.