All sounds, whether articulate or inarticulate, are produced by the meeting of [800a1] bodies or of the air with bodies, not because the air assumes certain shapes, as some people think, but because it is set in motion in the way in which, in other cases, bodies are moved, whether by contraction or expansion or compression, or again [5] when it clashes together by an impact from the breath or from the strings of musical instruments. For, when the nearest portion of it is struck by the breath which comes into contact with it, the air is at once driven forcibly on, thrusting forward in like manner the adjoining air, so that the sound travels unaltered in quality as far as the disturbance of the air manages to reach. For, though the disturbance originates at a [10] particular point, yet its force is dispersed over an extending area, like breezes which blow from rivers or from the land. Sounds which happen for any reason to have been stifled where they arise, are dim and misty; but, if they are clear, they travel far and [15] fill all the space around them.
We all breathe in the same air, but the breath and the sounds which we emit differ owing to the differences among the vessels involved, through which the breath must travel in its passage from within—namely, the windpipe, the lungs, and the [20] mouth. Now the impact of the breath upon the air and the shapes assumed by the mouth make most difference to the voice. This is clearly the case; for indeed all the differences in the kinds of sounds which are produced proceed from this cause, and we find the same people imitating the noise of horses, of frogs, of the nightingale, of [25] cranes, and of practically every other living creature, by means of the same breath and windpipe, merely by expelling the air from the mouth in different ways. Many birds also imitate by these means the cries of other birds which they hear. [30]
As to the lungs, when they are small and thick and hard, they cannot admit the air nor expel it again in large quantities, nor is the impact of the breath strong and vigorous. For, because they are hard and thick and constricted, they do not admit of [35] dilatation to any great extent, nor again can they force out the breath by contracting after wide distension; just as we ourselves cannot produce any effect with bellows, when they have become hard and cannot easily be dilated and closed. [800b1] For what gives strength to the impact of the breath is that the lungs after wide distension contract and violently force out the air. This can be illustrated from the [5] other parts of the body, none of which can strike a blow with any effect at a very close distance. It is impossible with either the leg or the hand to smite the object of [10] your blow with any force or to hurl it far, unless you allow the limb a considerable distance in which to strike the blow. If you fail to do so, the blow is hard owing to the energy exerted, but it cannot force its object far. Under similar circumstances stone-throwing engines cannot shoot far, nor a sling, nor a bow, if it is stiff and will [15] not bend, and the string cannot be drawn back far. But if the lung is large and soft and flexible, it can admit the air and expel it again in large quantities, regulating it at will, thanks to its softness and the ease with which it can contract.
[20] As for the windpipe, when it is long and narrow, it is only with difficulty that the voice is emitted, and considerable force is required owing to the distance that the breath has to travel. This is clear from the fact that creatures which have long necks force out their cries—geese, for example, and cranes and domestic fowls. A [25] better illustration may be taken from the pipe; every one, for instance, finds a difficulty in filling the ‘silkworm’ pipe, and considerable exertion is required owing to the amount of space to be filled. Furthermore, owing to narrowness of the passage, the breath is compressed within, and on escaping immediately expands and [30] disperses, like streams when they pass through narrow straits; so that the voice is not sustained and does not carry far. Moreover, in such cases the breath must necessarily be hard to regulate and not easily controlled. On the other hand, when [35] the windpipe is of considerable width, the breath can pass out easily, but, whilst travelling within, it becomes dispersed owing to the abundance of space, and the [801a1] voice becomes hollow and lacks solidity; furthermore, creatures which have wide windpipes cannot differentiate clearly with their breath because the windpipe does not hold firmly together. Creatures in whom the windpipe is irregular and has not the same width throughout must suffer from difficulties of every kind; for their [5] breath must be under irregular control, and must be compressed in one part and dispersed again in another part. If the windpipe is short, it necessitates a quick expulsion of the breath, and the impact on the air is more violent; in such cases the voice is higher owing to the quick passage of the breath.
[10] Not only differences among the vessels make a difference to the voice, but also their condition. When the lungs and the windpipe are full of moisture, the breath is dispersed and does not pass out continuously, because it sticks and becomes thick [15] and moist and difficult to move, as happens in the case of a catarrh and in drunkenness. If the breath be absolutely dry, the voice becomes rather hard and dispersed; for moisture, when it is slight, holds the air together and causes, as it were, a unity in the voice. Such, then, are the differences in the voice caused by [20] variations in the vessels and their conditions.
Now though we localize sounds where they severally originate, yet in every case we actually hear them only when they strike upon the ear; for the air struck by [25] the impact is borne along for a certain distance in a mass, and then gradually becomes dispersed, and we hereby distinguish all sounds as near or distant. This can be illustrated by the fact that if a man takes a pot1 or a pipe or a trumpet and holds it [30] up to another man’s ear and speaks through it, all the sounds seem quite close to the ear, because the air passing along the tube is not dispersed and the sound is kept uniform by the instrument which encloses it. Just as in a picture, if an artist represents two objects in colour, one as though it were at a distance and the other as though it were close at hand, the former object appears to us to be sunk into the [35] background of the picture and the latter to stand out in the foreground, though they are really in the same plane; so, too, in the case of sounds, whether articulate or inarticulate, if one sound is already dissolved before it strikes the ear, whilst another still retains its continuity, though both reach the same spot, the former seems distant from the ear and the latter quite near to it, because the one resembles a sound coming from afar, the other a sound2 close at hand. [801b1]
Voices are distinct in proportion to the accuracy of the sounds uttered; for it is impossible for the voice to be distinct if the sounds are not perfectly articulated, just as the sealings of signet-rings cannot be distinct unless they are accurately impressed. For this reason children cannot speak distinctly, nor drunken persons, [5] nor old people, nor those who naturally lisp, nor, speaking generally, those whose tongues and mouths have any defect of movement. For as in instrumental music the sound produced by the combination of brass instruments and horns is less distinct, [10] so too, in the case of speech, great indistinctness is caused by the escape of breath from the mouth if the sounds are irregularly formed. They not only present themselves indistinctly, but they also impede the carefully articulated sounds, because the movement to which they give rise, and which affects the ear, is [15] irregular. Therefore, when we hear one person speaking, we understand better than when we hear a number of persons saying the same thing at the same time. The same is the case with stringed instruments; and we hear still less well when the oboe and lyre are played at the same time, because the sounds confuse one another. This is particularly evident when they are played in harmony, the result being that the [20] two sounds produced drown one another. The conditions under which sounds become indistinct have now been stated.
Clearness in sound resembles clearness in colour. Those colours which most affect the eye are most clearly seen; in like manner we must suppose that those [25] sounds are most clearly heard which are most able to affect the hearing, when they strike upon it, in other words sounds which are distinct and solid and pure, and have most power of penetration; for indeed it is a general truth of sense-perceptions that the most distinct impressions are produced by the strongest, solidest, and purest [30] stimuli. This is borne out by the fact that all sounds finally become dim as the air which carries them becomes dispersed. The point can also be illustrated from the oboe; the sounds produced by oboes which have sloping reeds in their mouthpieces3 are softer, but not so clear; for the breath being forced down passes immediately [35] into a wide space and is not continuously and consistently sustained, but becomes dispersed. But when the reeds are closely constructed, the sound produced is harder and clearer, the more one presses them against the lips, because the breath is thus emitted with more violence. Such, then, are the conditions of clearness in the voice. So voices which are called ‘grey’ are generally considered no worse than those which [802a1] are called ‘white’. For voices which are rather harsh and slightly confused and have not any very marked clearness are the fitting accompaniment of outbreaks of [5] passion and of advancing years, and at the same time, owing to their intensity, they are less under control; for what is produced by violent exertion is not easily regulated, for it is difficult to increase or decrease the strength of the sound at will.
In the case of oboes and other instruments of the same class, the sounds produced are clear when the breath emitted from them is concentrated and intense. [10] For the impacts on the external air must be of this kind, and it is in this way that they will best travel to the ear in a solid mass. Similarly, in the case of odours and light and the various forms of heat, the weaker they are, the less definite is the impression which they convey to the sense-perception, just as juices are weaker [15] when mixed with water or with other juices. For that which provides a perception of itself makes the powers in each case obscure.
In contrast to all other musical instruments the notes produced by horns, if they strike the air in a solid and continuous mass, are indistinct. Therefore the horn [20] ought to be one the nature of whose growth is regular and smooth, and which does not shoot up quickly. For such horns as shoot up quickly must necessarily be too soft and spongy, so that the notes are dispersed and do not pass out in a solid mass, nor do they produce a consistent sound owing to the softness and thinness of the pores. [25] On the other hand, the horn must not be of too slowly growing a kind, nor must it be of a thick, hard consistency and lacking in resonance; for, if the sound in its passage strikes against anything, it is arrested at the point and ceases to advance on its outward course, so that the notes which proceed from such horns are dull and [30] irregular. That the direction taken by sound follows a straight line is clear from the way in which carpenters test beams and large timber in general. For when they strike one end, the sound passes along continuously to the other end unless the wood [35] has some flaw in it; if it has a flaw, the sound travels along up to that point and there ceases and is dispersed. It passes round the knots in the wood and cannot continue in a straight course through them. The point can also be illustrated from what happens in bronze-working when they are filing down the loosely hanging folds of drapery or the wings of statues; the cracks close up, so that the metal gives out a rasping sound [40] and causes a considerable noise; but the sound immediately ceases if you tie a band round the folds; for the vibration continues till it strikes the soft material and is there checked.
[802b1] The baking of horns contributes greatly to the excellence of their tone; for, when they are well baked, they produce a sound very like that of pottery, owing to [5] the hardness and the baking; whilst, if they are not sufficiently baked, the sound which they make is too gentle owing to the softness of the horn, and they cannot produce such well-defined notes. Men, therefore, choose the ages of their horns; the horns of old animals are dry and callous and porous, while those of young animals [10] are quite soft and contain a considerable amount of moisture. As we have said, a horn should be dry, of uniform thickness, with straight pores and a smooth surface; for if it be so, the notes which pass through it will be full and smooth and even, and the impacts which they make upon the outer air will have the same qualities. For those strings too are best which are smoothest and most even all along, and show the [15] same workmanship throughout, and in which the joining of the gut is not visible; for then the impacts which they make upon the air are most even.
The reeds of oboes, too, must be solid and smooth and even, so that the breath may pass through smoothly and evenly, without being dispersed. Therefore [20] mouthpieces which have been well steeped and soaked in grease give a pleasant sound, while those which are dry produce less agreeable notes. For the air passes softly and evenly through a moist and smooth instrument. This is clear from the fact that the breath itself, when it contains some moisture, is less likely to strike against [25] the mouthpiece and become dispersed; while dry breath is inclined to catch in the oboe, and the impact which it causes is too hard owing to the force necessary to expel it. Differences, then, in sound arise from the above causes.
Hard voices are those which strike forcibly upon the hearing; for which reason [30] they are particularly unpleasing—those, that is to say, which are difficult to start, but which when once started travel with added force—for any quickly yielding body which comes in the way fails to abide the impact and quickly springs aside. To take an illustration of this; heavy missiles travel along with force, as do streams when [35] they pass through narrow channels, for they acquire very considerable force in the actual straits, because they cannot yield to restraint all in a moment, but are driven violently along. The same thing happens in the case of articulate and inarticulate sounds. For clearly all forceful sounds are hard; as, for instance, those caused by the forcible opening of boxes and turning of hinges, and those made by bronze and iron. [40] For the sound made on the anvil is hard when the iron that is being forged is chilled and has become hard. So, too, is the noise from the file, when they are filing iron [803a1] implements and making teeth in saws. The most violent claps of thunder, too, produce very hard sounds, and those showers which from their violence we call ‘tearing’ showers.
It is quickness of breathing which makes the voice shrill, force which makes it [5] hard. So it happens that the same individuals have not only sometimes a shriller and at other times a deeper voice, but also at times a harder and at times a softer voice. Yet some people hold that it is owing to the hardness of the windpipe that the voice becomes hard. In this they are wrong; for, though this may be quite a slight [10] contributing cause, the real reason is the force of the impact caused by the breath from the lungs. For as some men’s bodies are moist and soft, while those of others are hard and closely knit, so do their lungs show variety. Therefore in some cases the [15] breath which comes forth is soft, in others it is hard and violent; for it is easy to see that the windpipe by itself exercises but little influence. For no windpipe is of the hard consistency of an oboe; yet for all that, by passing the breath through the former and through the latter, some people produce soft and others hard tones on [20] the oboe. This is clear from the direct perception; for, if by using greater force one increases the strength of the breathing, the voice immediately becomes harder as a result of the force applied, even if it be a somewhat soft voice. So, too, in the case of the trumpet; when they are revelling, men relax the pressure of breath in the [25] trumpet in order to make the sound as soft as possible. The point can also be illustrated from musical instruments; as has been stated, the sounds produced by tightly stretched strings are hard, as are the notes of horns which have been well [30] baked. If one touches the strings violently instead of softly with the hand, they necessarily respond with more violent sounds. The notes produced by less tightly stretched strings and unbaked horns are softer, as are those produced by the longer [35] musical instruments; for the impacts upon the air are both slower and softer owing to the distance that the sound has to travel, whereas in the shorter instruments they are harder owing to the tension of the strings. That this is so is shown by the fact that the sounds which the instrument itself gives forth are harder when one does not strike the string in the middle, because there is more strain upon the parts of the [40] strings near the crossbar and near the pegs. The notes produced by instruments made of fennel are softer; for the sounds striking on a soft material do not rebound [803b1] with such violence.
Voices are rough when the impact of all the breath upon the air is not single but divided and dispersed. For each portion of the air striking separately upon the [5] hearing—as if each were moved by a different impact—the sense-impression is dispersed, so that one vocal utterance fails to produce any sound, while another strikes with great violence upon the ear, and the contact with the hearing is not [10] evenly sustained; just as when a rough object touches the skin. This can be best illustrated from the file; for the air is set in motion simultaneously at a number of separate minute points, and so the sounds passing from these points to strike the ear seem rough, and especially so when the file is scraped against a hard substance. One may compare the sense of touch; hard, rough objects produce perception more [15] forcefully. The matter can also be illustrated from the pouring of liquids, for the sound made by olive-oil is less noticeable than that made by any other liquid, owing to the continuity of its parts.
Voices are thin, when the breath that is emitted is small in quantity. Children’s [20] voices, therefore, are thin, and those of women and eunuchs, and in like manner those of persons who are enfeebled by disease or over-exertion or want of nourishment; for owing to their weakness they cannot expel the breath in large quantities. The same thing may be seen in the case of stringed instruments; the sounds produced from thin strings are thin and narrow and fine as hairs, because [25] the impacts upon the air have only a narrow surface of origin. For the sounds that are produced and strike on the ear are of the same quality as the source of movement which gives rise to the impacts; for example, they are rare or dense, soft [30] or hard, thin or full. For one portion of the air striking upon another portion of the air preserves the quality of the sound, as is the case also in respect of shrillness and depth; for the quick impulsions of the air caused by the impact, quickly succeeding one another, preserve the quality of the voice, as it was in its first origin. Now the [35] impacts upon the air from strings are many and are distinct from one another, but because, owing to the shortness of the intermittence, the ear cannot appreciate the intervals, the sound appears to us to be united and continuous. The same thing is the case with colours; for separate coloured objects appear to join, when they are moved [804a1] rapidly. The same thing happens, too, when notes form a concord; for owing to the fact that the notes overlap and include one another and cease at the same moment, the intermediate sounds escape our notice. For in all concords more frequent impacts upon the air are caused by the shriller note, owing to the quickness of its movement; and the last note strikes upon our hearing simultaneously with an earlier sound produced by the slower impact. Thus, because, as has been said, the ear [5] cannot perceive all the intermediate sounds, we seem to hear both notes together and continuously.
Thick sounds, on the contrary, are produced when the breath is emitted in great quantity and all together. Therefore the voices of men are inclined to be thick, [10] and the notes of the so-called ‘perfect’ oboes, especially when the latter are well filled with air. This is clear from the fact that if you compress the mouthpiece the sound tends to become shrill and thin, as also if one draws the ‘speaker’ downwards; but if one stops up the exits, the volume of the sound becomes far greater owing to [15] the amount of breath, like the notes produced from thicker strings. The sounds uttered by those whose voices are breaking and persons suffering from sore-throats, and after vomiting, are thick owing to the roughness of the windpipe and the fact that the voice does not escape, but striking upon it is pent up and acquires volume; [20] and above all, owing to the moist condition of the body.
Piping voices are those which are thin and concentrated, such as those of grasshoppers and locusts and the nightingale’s song, and, generally speaking, cries which are thin, and are not followed by a second and different sound. For this piping quality does not depend on volume of sound nor on the tones being without tension [25] and deep, nor yet upon the close sequence of the sounds, but rather upon shrillness and thinness and accuracy. Therefore it is the instruments which are lightly constructed and tightly stretched, and those which have no horn-work about them, that produce piping notes. The sound of running water, and generally speaking, any [30] sound which, whatever its cause keeps up an unbroken continuity, preserve the accuracy of their tone.
Cracked voices which suddenly give way are those which travel along in a solid mass for a certain distance and then become dispersed. The best illustration may be taken from an earthenware vessel; every such vessel when broken as the result of a blow gives forth a cracked sound, for the course of the sound is broken at the point at [35] which the blow was struck, so that the sounds which it gives forth no longer form a solid mass. The same thing happens in the case of broken horns and badly strung strings; in all such cases the sound travels in a solid mass up to a certain point and is then dispersed, wherever the medium which supports it is not continuous, so that the [804b1] impact upon the air is not single but dispersed, and the sound produced seems cracked. Cracked voices closely resemble harsh voices, except that in the latter case the sounds are themselves dispersed into small portions, while cracked voices, for [5] the most part, form a solid mass at first and afterwards become split up into a number of parts.
Aspirated sounds are formed when we emit the breath from within immediately together with the sounds; smooth sounds, on the contrary, are those which are [10] formed without the emission of the breath.
Voices become broken when they have no longer strength enough to expel the air with an impact, but the region about the lungs collapses after distension. For just as the legs and shoulders eventually collapse when they are in a strained position, so [15] too the region about the lungs. The breath comes forth lightly, because the impact which it produces is not forcible enough; at the same time, owing to the fact that the windpipe has become exceedingly rough, the breath cannot pass out in a solid mass, [20] but is dispersed, and so the sounds which it produces are broken. Some people hold that it is owing to the adhesive condition of the lungs that the breath cannot pass out and abroad; but they are wrong, for what really happens is that they make a sound but cannot be heard, because the impact upon the air does not take place with [25] sufficient energy, but they only make a sound such as the breath would make when forced merely from the throat.
When people stammer, it is due not to an affection of the veins or windpipe, but to the movement of the tongue; for they find a difficulty in changing the position of the tongue when they have to utter a second sound. They therefore keep on [30] repeating the same word, for they cannot utter the next word; but the movements of articulation continue and the lungs go on working with an impetus in the same direction as before, owing to the quantity and force of the breath. For just as when one is running fast it is difficult to divert the whole body from its impetus in one direction to some other movement, so likewise is it with the individual parts of the [35] body. So people who stammer are often unable to say the next word, but can easily say the next but one, when they make a fresh start to the movement. This is clear from the fact that people often stammer when angry, because then they force out their breath.