The Soundscape: Our Sonic Environment And The Tuning Of The World (24 page)

A sound spectrogram of a Canadian Pacific train whistle
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Acousticians Are the World’s Best Sightreaders
      I do fault acoustic or phonetic machines for their inability to solve the problem of the simultaneous representation of the total sound image. That the two-dimensional image is sufficient for many kinds of investigation has, as I will be showing later on, a correspondence in our perceptual tendency to identify a limited number of significant features in any sound heard. If I have kept my enthusiasm for sound visualization under control up to this point, it is simply because I want the reader to remain alert to the fact that
all visual projections of sounds are arbitrary and fictitious
. This becomes emphatically explicit if we ask people to draw selected sounds when they are played to them on tape, to draw them in real time without forethought. In such exercises musicians or acoustical engineers often observe the conventions of left to right for time and up and down for frequency, while those without this kind of training react more independently. For them a sound may begin anywhere on the page. It may be coiled in a circle or be splattered about everywhere.

Hermann Helmholtz stood on the threshold between the aural and the visual study of sound. The most engaging feature of his monumental book
On the Sensations of Tone
(1877) is his great love of sound (he was a friend of musicians and himself a performer); but he could also write, concerning the study of vibration:

To render the law of such motions more comprehensible to the eye than is possible by lengthy verbal descriptions, mathematicians and physicists are in the habit of applying a graphical method, which must be frequently employed in this work, and should therefore be well understood.

This strikes the pattern to be followed, and while the science of acoustics has advanced greatly since the nineteenth century, the listening abilities of average mortals have not shown corresponding improvement. In fact, they may have deteriorated in inverse proportion to the pictorialization of sound.

Today, many specialists engaged in sonic studies—acousticians, psychologists, audiologists, etc.—have
no
proficiency with sound in any dimension other than the visual. They merely read sound from sight. From my acquaintance with such specialists I am inclined to say that the first rule for getting into the sonics business has been to learn how to exchange an ear for an eye. Yet it is precisely these people who are placed in charge of planning the acoustic changes of the modern world.

A couple of years ago I was invited to speak at a symposium on transportation noise, organized by the U.S. Government. For several days acoustical engineers delivered papers on jet noise, fan noise, tire noise and so forth, illustrating their work with an ambitious array of slides and charts. Not a single sound was ever played as illustration. When I spoke, I began by reading back a catalogue of visual metaphors for sound from the researchers’ own speeches: “You can see from the next slide that the sound has decreased in intensity"—that kind of thing. The shock of realization for those present was strong. Today acoustics is merely the science of sightreading.

I would not be dragging this point over so many paragraphs if I did not anticipate that we are on the threshold of a change. Such a change will be consistent with the theme announced in McLuhan’s
The Gutenberg Galaxy:
“As our age translates itself back into the oral and auditory modes because of the electronic pressure of simultaneity, we become sharply aware of the uncritical acceptance of visual metaphors and models by many past centuries.” If McLuhan is right, we may expect to move away from our dependence on visual representation of sound just as we are leaving print culture. It was print culture which, in McLuhan’s view, moved the word away from its original association with sound and “treated it more as a ‘thing’ in space.” Just as the notation of music is now being replaced by the record player, the tape recorder is pushing the physical study of acoustics into the human area of psychoacoustics. And for general field work in measuring the intensity of sound, the flat response of the sound level meter (the so-called C scale) has given way to the contoured A scale, weighted along the lines of the equal loudness contours of the human ear. Similarly, the numerous refinements in measuring aircraft noise in recent years have tended more and more to take human response into consideration. Thus EPNdB (Effective Perceived Noise in Decibels) takes into account the particular tone components of aircraft as well as the duration of the noise, while NNI (Noise and Number Index) uses the EPNdB as a basis and additionally calculates the number of aircraft per day (or night) as a key annoyance factor.

The acoustical engineer may not yet be a listener but he is at least adapting his instrumentation to hear more the way we do.
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Sound Objects, Sound Events and Soundscapes
      Since the Second World War, tape recorders have been abundant in broadcasting studios, and so it was that when the first psychoacoustic experiments were undertaken by the research group of the French radio in Paris in 1946, the director, Pierre Schaeffer, made good use of them. Although a mechanical engineer by training, Schaeffer never surrendered his ears for his eyes. This preoccupation with sound as sound is evident in his definition of the sound object
(l’objet sonore)
, a term which he invented and defined as an acoustical “object for human perception and not as a mathematical or electroacoustical object for synthesis.” We may call the sound object the smallest self-contained particle of a soundscape. Because it possesses a beginning, middle and end, it is analyzable in terms of its envelope. Envelope is a graphic term but the ear can be trained to hear its characteristics, which are defined as attack, body (or stationary state) and decay.

A few remarks about each of these components will not be out of place. The attack is the onset portion of the sound object. When a system is suddenly excited, an enrichment of the spectrum results, giving a rough or dissonant edge to the sound. Thus every attack of sound is accompanied by noise, and the more suddenly it appears, the more noise is present—a fact which is especially significant in electroacoustical systems with their brief switch-on times. When a sound develops more slowly, less of this sudden spectral excitement is present and an even tone quality emerges. Many musical instruments have varying modes of attack, but some have a natural tendency to “speak” more quickly than others: compare the mandolin and the violin. The onset-transients of the attack may be only a few milliseconds long, but their importance in terms of characterizing the sound should never be underestimated. In fact, as Schaeffer and his colleagues demonstrated, when the attack portions of certain sounds are amputated, they may become wholly unintelligible or may be mistaken for others (a piano may then sound like a flute or a bassoon like a cello).

The middle portion of the sound object used to be called the stationary or steady-state portion, but it is better to call it the body, because nothing about sound is ever really stationary. Nevertheless, there may appear to be a period in the midlife of a sound when to the naked ear the sound seems unprogressive and stationary. Some sounds, such as bells, gongs, pianos and percussion instruments, have no apparent body, consisting exclusively of attack and decay. Other sounds, such as that of the air-conditioner, remain exclusively in the intermediate or stationary state. They do not die. This is an artificial condition, initiated, as I have already said, by the factories of the nineteenth century and extended by the Electric Revolution into all corners of modern living.

The bio-acoustic analogies I have just introduced are not merely personal ramblings, for the relationship between the two disciplines is made explicit in the term
decay
. The energy of a sound weakens; it withers and dies. There are rapid decays and there are infinitely slow decays.

The decay is usually combined with some sensation of reverberation. W. C. Sabine, the acoustician, has defined reverberation time technically. It is the time that elapses from the instant a sound source is switched off until its energy decays to one millionth of its original strength (a drop of 60 decibels). As far as the ear is concerned, it is the time it takes for a sound to melt and be lost in the ambient noise. Echo differs from reverberation in that it is a repetition or partial repetition of a sound, due to reflection off a distant surface. Reverberation is also reflected sound but no separate repetitions of the original are distinguishable.

Although the sound object may thus be subdivided for purposes of ear training, it must nevertheless always be considered integrally. Schaeffer: “A composed structure (such as we perceive it) cannot be deduced from separate perceptions of its component objects.” But Schaeffer deliberately excludes all considerations of the sound object in any but physical and psychophysical terms. He does not want to confuse the study of sounds by considering their semantic or referential aspects. That a bell sound comes from a bell does not interest him. To him it is a phenomeno-logical sound formation only. “The sound object must not be confused with the sounding body by which it is produced,” for one sounding body “may supply a great variety of objects whose disparity cannot be reconciled by their common origin.”

The limitations of such a clinical approach for soundscape studies will be obvious, and though soundscape researchers will want to be familiar with such work, we will be equally concerned with the referential aspects of sounds and also with their interaction in field contexts. When we focus on individual sounds in order to consider their associative meanings as signals, symbols, keynotes or soundmarks, I propose to call them
sound events
, to avoid confusion with
sound objects
, which are laboratory specimens. This is in line with the dictionary definition of
event
as “something that occurs in a certain place during a particular interval of time"—in other words, a context is implied. Thus the same sound, say a church bell, could be considered as a sound object if recorded and analyzed in the laboratory, or as a sound event if identified and studied in the community.

The soundscape is a field of interactions, even when particularized into its component sound events. To determine the way sounds affect and change one another (and us) in field situations is immeasurably more difficult a task than to chop up individual sounds in a laboratory, but this is the important and novel theme now lying before the soundscape researcher.

Aerial Sonography
      The question is, which types of notation will be most helpful in these pursuits? At present there can be no grand solutions to this problem, for research is only beginning. It would be useful to have a notation or notations which could be read and comprehended immediately by professionals in many fields, particularly those on whom soundscape studies impinge most closely: i.e., architects, urbanologists, sociologists and psychologists as well as musicians and acousticians.

The best way to appreciate a field situation is to get above it. The medieval cartographer did this by climbing the highest hill, and the Mannerist painters of the Renaissance expanded the vistas of their paintings by doing the same thing. Surely one of the greatest inventions of man was the aerial projection in cartography, which represented a far bolder leap of the imagination than the fumbling exercises that eventually resulted in the actuality of flight.

One example of aerial projection applied to sound intensity is the isobel contour map. The isobel map derives from the contour maps of geographers and meteorologists, and consists of hundreds or thousands of readings on a sound level meter averaged out to produce bars of equal intensity, projected as if the observer were above the field of study. On such a map the quietest and noisiest sections of a territory can be immediately identified.
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