Sound Research WIKINDX

The definition has the following footnote: "Not all sounds evoke an auditory sensation, e.g., ultrasound or infrasound. Not all auditory sensations are evoked by sound, e.g., tinnitus."

"Sound may mean either of two things (a) actual, and (b) potential, sound. There are certain things which, as we say, 'have no sound', e.g. sponges or wool, others which have, e.g. bronze and in general all things which are smooth and solid-the latter are said to have a sound because they can make a sound, i.e. can generate actual sound between themselves and the organ of hearing. 

Actual sound requires for its occurrence (i, ii) two such bodies and (iii) a space between them; for it is generated by an impact. Hence it is impossible for one body only to generate a sound-there must be a body impinging and a body impinged upon; what sounds does so by striking against something else, and this is impossible without a movement from place to place. 

As we have said, not all bodies can by impact on one another produce sound; impact on wool makes no sound, while the impact on bronze or any body which is smooth and hollow does. Bronze gives out a sound when struck because it is smooth; bodies which are hollow owing to reflection repeat the original impact over and over again, the body originally set in movement being unable to escape from the concavity.

Further, we must remark that sound is heard both in air and in water, though less distinctly in the latter. Yet neither air nor water is the principal cause of sound. What is required for the production of sound is an impact of two solids against one another and against the air. The latter condition is satisfied when the air impinged upon does not retreat before the blow, i.e. is not dissipated by it.

That is why it must be struck with a sudden sharp blow, if it is to sound-the movement of the whip must outrun the dispersion of the air, just as one might get in a stroke at a heap or whirl of sand as it was traveling rapidly past. 

An echo occurs, when, a mass of air having been unified, bounded, and prevented from dissipation by the containing walls of a vessel, the air originally struck by the impinging body and set in movement by it rebounds from this mass of air like a ball from a wall. It is probable that in all generation of sound echo takes place, though it is frequently only indistinctly heard. What happens here must be analogous to what happens in the case of light; light is always reflected-otherwise it would not be diffused and outside what was directly illuminated by the sun there would be blank darkness; but this reflected light is not always strong enough, as it is when it is reflected from water, bronze, and other smooth bodies, to cast a shadow, which is the distinguishing mark by which we recognize light. 

It is rightly said that an empty space plays the chief part in the production of hearing, for what people mean by 'the vacuum' is the air, which is what causes hearing, when that air is set in movement as one continuous mass; but owing to its friability it emits no sound, being dissipated by impinging upon any surface which is not smooth. When the surface on which it impinges is quite smooth, what is produced by the original impact is a united mass, a result due to the smoothness of the surface with which the air is in contact at the other end.

What has the power of producing sound is what has the power of setting in movement a single mass of air which is continuous from the impinging body up to the organ of hearing. The organ of hearing is physically united with air, and because it is in air, the air inside is moved concurrently with the air outside. Hence animals do not hear with all parts of their bodies, nor do all parts admit of the entrance of air; for even the part which can be moved and can sound has not air everywhere in it. Air in itself is, owing to its friability, quite soundless; only when its dissipation is prevented is its movement sound. The air in the ear is built into a chamber just to prevent this dissipating movement, in order that the animal may accurately apprehend all varieties of the movements of the air outside. That is why we hear also in water, viz. because the water cannot get into the air chamber or even, owing to the spirals, into the outer ear. If this does happen, hearing ceases, as it also does if the tympanic membrane is damaged, just as sight ceases if the membrane covering the pupil is damaged. It is also a test of deafness whether the ear does or does not reverberate like a horn; the air inside the ear has always a movement of its own, but the sound we hear is always the sounding of something else, not of the organ itself. That is why we say that we hear with what is empty and echoes, viz. because what we hear with is a chamber which contains a bounded mass of air.

Which is it that 'sounds', the striking body or the struck? Is not the answer 'it is both, but each in a different way'? Sound is a movement of what can rebound from a smooth surface when struck against it. As we have explained' not everything sounds when it strikes or is struck, e.g. if one needle is struck against another, neither emits any sound. In order, therefore, that sound may be generated, what is struck must be smooth, to enable the air to rebound and be shaken off from it in one piece. 

The distinctions between different sounding bodies show themselves only in actual sound; as without the help of light colours remain invisible, so without the help of actual sound the distinctions between acute and grave sounds remain inaudible. Acute and grave are here metaphors, transferred from their proper sphere, viz. that of touch, where they mean respectively (a) what moves the sense much in a short time, (b) what moves the sense little in a long time. Not that what is sharp really moves fast, and what is grave, slowly, but that the difference in the qualities of the one and the other movement is due to their respective speeds. There seems to be a sort of parallelism between what is acute or grave to hearing and what is sharp or blunt to touch; what is sharp as it were stabs, while what is blunt pushes, the one producing its effect in a short, the other in a long time, so that the one is quick, the other slow. 

Let the foregoing suffice as an analysis of sound. Voice is a kind of sound characteristic of what has soul in it; nothing that is without soul utters voice, it being only by a metaphor that we speak of the voice of the flute or the lyre or generally of what (being without soul) possesses the power of producing a succession of notes which differ in length and pitch and timbre. The metaphor is based on the fact that all these differences are found also in voice. Many animals are voiceless, e.g. all non-sanuineous animals and among sanguineous animals fish. This is just what we should expect, since voice is a certain movement of air. The fish, like those in the Achelous, which are said to have voice, really make the sounds with their gills or some similar organ. Voice is the sound made by an animal, and that with a special organ. As we saw, everything that makes a sound does so by the impact of something (a) against something else, (b) across a space, (c) filled with air; hence it is only to be expected that no animals utter voice except those which take in air. Once air is inbreathed, Nature uses it for two different purposes, as the tongue is used both for tasting and for articulating; in that case of the two functions tasting is necessary for the animal's existence (hence it is found more widely distributed), while articulate speech is a luxury subserving its possessor's well-being; similarly in the former case Nature employs the breath both as an indispensable means to the regulation of the inner temperature of the living body and also as the matter of articulate voice, in the interests of its possessor's well-being. Why its former use is indispensable must be discussed elsewhere. 

The organ of respiration is the windpipe, and the organ to which this is related as means to end is the lungs. The latter is the part of the body by which the temperature of land animals is raised above that of all others. But what primarily requires the air drawn in by respiration is not only this but the region surrounding the heart. That is why when animals breathe the air must penetrate inwards.

Voice then is the impact of the inbreathed air against the 'windpipe', and the agent that produces the impact is the soul resident in these parts of the body. Not every sound, as we said, made by an animal is voice (even with the tongue we may merely make a sound which is not voice, or without the tongue as in coughing); what produces the impact must have soul in it and must be accompanied by an act of imagination, for voice is a sound with a meaning, and is not merely the result of any impact of the breath as in coughing; in voice the breath in the windpipe is used as an instrument to knock with against the walls of the windpipe. This is confirmed by our inability to speak when we are breathing either out or in-we can only do so by holding our breath; we make the movements with the breath so checked. It is clear also why fish are voiceless; they have no windpipe. And they have no windpipe because they do not breathe or take in air. Why they do not is a question belonging to another inquiry."

'Common sensibles' are movement, rest, number, figure, magnitude; these are not peculiar to any one sense, but are common to all. There are at any rate certain kinds of movement which are perceptible both by touch and by sight. 

We speak of an incidental object of sense where e.g. the white object which we see is the son of Diares; here because 'being the son of Diares' is incidental to the directly visible white patch we speak of the son of Diares as being (incidentally) perceived or seen by us. Because this is only incidentally an object of sense, it in no way as such affects the senses. Of the two former kinds, both of which are in their own nature perceptible by sense, the first kind-that of special objects of the several senses-constitute the objects of sense in the strictest sense of the term and it is to them that in the nature of things the structure of each several sense is adapted."

It seems that there is always some echo, but not always a clear one. For the same occurs with sound as with light; which also is always reflected

Aquinas claims that there is air on both sides of the eardrum, and that when we hear the inner air echoes the outer sound. Echoes, Aquinas may have thought, are like reflections in that (a) when you hear a whistle echo off a canyon wall the rock is not sounding (as the mirror does not become red)-it is the whistle that is making the noise; (b) the whistle causes the echo; and (c) when you hear the echo you are hearing the whistle."

"To excite in us tastes, odors, and sounds I believe that nothing is required in external bodies except shapes, numbers, and slow or rapid movements. I think that if ears, tongues, and noses were temporarily removed, shapes and numbers and motions would remain, but not odors or tastes or sounds. The latter, I believe, are nothing more than names when separated from living beings [...] many sensations which are supposed to be qualities residing in external objects have no real existence save in us" (p.277).

From the 1957 translation: Galilei, Galileo, 1623 [1957], Il Saggiatore (The Assayer), Rome. Translated in Discoveries and Opinions of Galileo, Stillman Drake (trans.), New York: Anchor Books, 1957.

Italian version (NB text recognition so some misrecognition e.g. 'u' for 'v'):
"Resta poi l'elemento dell'aria per li suoni, i quali indifferentemente vengono à noi dalle parti basse, e dall'alte, e dalle Laterali, essendo noi constituiti nell'aria, il cui mouimento in se stessa, cioè nella propria regione, è egualmente disposto per tutti i versi, e la situazion dell'orecchio è accommodata il più, che sia possibile, à tutte le positure di luogo, ed i suoni all'ora son fatti e sentiti in noi, quando (senz'altre qualità sonore, ò transonore) vn frequente tremor dell'aria in minutissime onde increspata muoue certa cartilaggine di certo timpano, ch'è nel nostro orecchio. Le maniere poi esterne potenti à far questo increspamento nell'aria sono moltissime, le quali forse si riducono in gran parte al tremore di qualche corpo, che vrtando nell'aria, l'increspa, e per essa con gran velocità si distendono l'onde, dalla frequenza delle quali nasce l'acutezza del suono, e la grauità dalla rarità."

"Mà che ne' corpi esterni per eccitare in noi i sapori, gli odori, e i suoni, si richiegga altro, che grandezze figure, moltitudini, e mouimenti, tardi ò veloci, io non lo credo; e stimo, che tolti via gli orecchi, le lingue, e i nasi, restino bene le figure, i numeri, e i moti, mà non già gli odori, ne i sapori, ne i suoni, li quali fuor dell'animal viuente, non credo, che sieno altro, che nomi [...] E tornando al primo mio proposito in questo luogo, auendo già veduto, come molte affezzioni, che sono riputate qualità risedenti ne' soggetti esterni, non anno veramente altra essistenza che in noi"

Distinguishes between musical listening (perception of a sound based on its pitch, loudness, temporal change, timbre and masking) and everyday listening (perception of the sound event itself and its environment). This is an experiential distinction or a perceptual one since any sound can be listened to in either listening mode. cf. Chion (1994, pp.25–34) etc.