CHAPTER VIII. Sound may be regarded from two aspects, either as potential or as actual for there are some things which we say have no sound, as for example sponge and wool, whereas we say that others have, as for example bronze and all hard and smooth substances, because they possess potentially the power of making sound that is, they are able actually to create a sound between the thing sounding and the sense of hearing. As for actual sound, it is always of something on something and within something, for it is a stroke which produces sound. Hence also it is impossible for sound to take place with only one object; since the object striking must be different from the object struck. Thus the object sounding sounds upon something: and the stroke does not take place without some movement. It is not however, as has been already said, the striking of any object whatever that produces sound: wool, for instance, produces no sound when struck, but bronze and all objects that are smooth and hollow do So. Bronze does so because it is smooth: hollow substances produce many sounds after the first blow, from their reverberation, because the air that has been put in movement cannot find an exit. Further, sound is heard in air, and in a less degree in water. It is however neither air nor water that is the essential condition of sound: there must be a percussion of solid bodies against each other and also against the air, as happens when the air that has been struck remains and is not dissipated. Thus the air emits a sound if it be struck quickly and vehemently: that is, the movement of the person striking must precede the dispersion of the air, just in the same way as one would have to strike quickly a heap or line of sand in motion so as to anticipate its dispersion. An echo is formed when, from air which has been compressed into one mass by some receptacle which has bounded it and prevented it from being dissipated, the air constituting sound is repelled back again, just as a ball may be made to rebound. It appears in fact that an echo is always formed, though it is not always distinct and audible: and this is because the same thing καθάπερ καὶ ἐπὶ τοῦ φωτός· καὶ γὰρ τὸ φῶς ἀεὶ ἀνακλα ται (οὐδὲ γὰρ ἂν ἐγίνετο πάντῃ φῶς, ἀλλὰ σκότος ἔξω τοῦ 30 ἡλιουμένου), ἀλλ' οὐχ οὕτως ἀνακλάται ὥσπερ ἀφ ̓ ὕδατος ἢ χαλκοῦ ἢ καί τινος ἄλλου τῶν λείων, ὥστε σκιὰν ποιεῖν, § 5 ἢ τὸ φῶς ὁρίζομεν. τὸ δὲ κενὸν ὀρθῶς λέγεται κύριον τοῦ ἀκούειν. δοκεῖ γὰρ εἶναι κενὸν ὁ ἀήρ, οὗτος δ ̓ ἐστιν ὁ ποιῶν ἀκούειν, ὅταν κινηθῇ συνεχὴς καὶ εἷς. ἀλλὰ διὰ τὸ ψαθυρὸς 35 εἶναι οὐ γεγωνεῖ, ἂν μὴ λεῖον ᾖ τὸ πληγέν. τότε δὲ εἷς γί- 420 νεται ἅμα διὰ τὸ ἐπίπεδον· ἓν γὰρ τὸ τοῦ λείου ἐπίπεδον. § 6 ψοφητικὸν μὲν οὖν τὸ κινητικὸν ἑνὸς ἀέρος συνεχείᾳ μέχρις ἀκοῆς, ἀκοὴ δὲ συμφνὴς ἀέρι. διὰ δὲ τὸ ἐν ἀέρι εἶναι, κι νουμένου τοῦ ἔξω τὸ εἴσω κινεῖ. διόπερ οὐ πάντῃ τὸ ζῷον ἀκούει, 5 οὐδὲ πάντῃ διέρχεται ὁ ἀήρ· οὐ γὰρ πάντῃ ἔχει ἀέρα τὸ κινησόμενον μέρος καὶ ἔμψυχον. αὐτὸ μὲν δὴ ἄψοφον ὁ ἀὴρ διὰ τὸ εὔθρυπτον· ὅταν δὲ κωλυθῇ θρύπτεσθαι, ἡ τούτου κίνησις ψόφος. ὁ δ ̓ ἐν τοῖς ὠσὶν ἐγκατῳκοδόμηται πρὸς τὸ ἀκίνητος εἶναι, ὅπως ἀκριβῶς αἰσθάνηται πάσας τὰς δια- το φορὰς τῆς κινήσεως. διὰ ταῦτα δὲ καὶ ἐν ὕδατι ἀκούομεν, ὅτι οὐκ εἰσέρχεται πρὸς αὐτὸν τὸν συμφυῆ ἀέρα· ἀλλ ̓ οὐδ ̓ εἰς τὸ οὖς διὰ τὰς ἕλικας. ὅταν δὲ τοῦτο συμβῇ, οὐκ ἀκούει· οὐδ ̓ ἂν ἡ μήνιγξ κάμῃ, ὥσπερ τὸ ἐπὶ τῇ κόρῃ δέρμα ὅταν κάμῃ. ἀλλὰ καὶ σημεῖον τοῦ ἀκούειν ἢ μὴ τὸ 15 30. οὐ STUVX Ald. 420 4. ἀκοῇ δὲ συμφυὴς ἀὴρ Wy. Tor. 5. ὁ εἴσω κινεῖται Tor., ὁ ETW, κινείται EUX. 7. ἔμψυχον] coni. Tor. ἔμψοφον. Η ὥσπερ ἡ κόρη τὸ ὑγρόν post ἔμψ. add. W et marg. U. 15. ὅταν κάμῃ om. EWy. happens to sound as happens also in the case of light. For light never ceases to be reflected: otherwise there would not be everywhere light, but (with the exception of that spot on which the sun's rays directly fall) darkness: only while light is thus continually reflected, it is not reflected in the same way as it is from water or bronze or any other polished substance, so as to produce the shadow, by which light is bounded. Vacuum or empty space is rightly said by some to be the indispensable vehicle of hearing: for the air is held to be empty, and it is this which causes hearing when it is put in movement as one continuous and connected body. At the same time, by reason of the easy dissipation of the air, no sound whatever is produced unless the object struck be smooth and polished in which case the air is made, through the even surface, one throughout, because the surface of every smooth body is one. Every object then so constituted as to set in movement the air extending continuously in one stream until it reach the hearing is sonorous, and hearing is itself attached by nature to the air: and because the sound is in the air, the movement of the air without sets in movement the air which is within. And hence an animal does not possess the sense of hearing in all parts of its body, nor does the air penetrate it at all places, because the organ which requires to move itself and is endowed with psychical capacity does not find everywhere that air on which its exercise depends. Thus then in itself the air is by reason of its ready dissipation soundless: but when it is prevented from dispersion, the movement of this compressed air produces sound. And the air contained within the ears is lodged deeply in them so that it may remain unmoved, and may thus perceive exactly all the different kinds of movement. Hence also the reason why we can hear in water, viz. because the water does not enter into the congenital air itself, nor even, in consequence of the convolutions, into the car itself: indeed, when this does happen, hearing becomes impossible. Nor again is hearing possible in case the membrane of the ear becomes exhausted, just as similarly vision is destroyed when the hard covering or cornea of the pupil is impaired. (It is in fact a test as to whether 20 ἠχεῖν αἰεὶ τὸ οὖς ὥσπερ τὸ κέρας· ἀεὶ γὰρ οἰκείαν τινὰ κίνησιν ὁ ἀὴρ κινεῖται ὁ ἐν τοῖς ὠσίν· ἀλλ ̓ ὁ ψόφος ἀλλότριος καὶ οὐκ ἴδιος. καὶ διὰ τοῦτό φασιν ἀκούειν τῷ κενῷ καὶ § 7 ἠχοῦντι, ὅτι ἀκούομεν τῷ ἔχοντι ὡρισμένον τὸν ἀέρα. πότερον δὲ ψοφεῖ τὸ τυπτόμενον ἢ τὸ τύπτον; ἢ καὶ ἄμφω, τρό- 10 πον δ ̓ ἕτερον· ἔστι γὰρ ὁ ψόφος κίνησις τοῦ δυναμένου νεῖσθαι τὸν τρόπον τοῦτον ὅνπερ τὰ ἀφαλλόμενα ἀπὸ τῶν λείων, ὅταν τις κρούσῃ. οὐ δὴ πᾶν, ὥσπερ εἴρηται, ψοφεῖ τυπτόμενον καὶ τύπτον, οἷον ἐὰν πατάξῃ βελόνη βελόνην ἀλλὰ δεῖ τὸ τυπτόμενον ὁμαλὸν εἶναι, ὥστε τὸν ἀέρα ἀθροῦν 25 § 8 ἀφάλλεσθαι καὶ σείεσθαι. αἱ δὲ διαφοραὶ τῶν ψοφούντων ἐν τῷ κατ' ἐνέργειαν ψόφῳ δηλοῦνται· ὥσπερ γὰρ ἄνευ φωτὸς οὐχ ὁρᾶται τὰ χρώματα, οὕτως οὐδ ̓ ἄνευ ψόφου τὸ ὀξὺ καὶ τὸ βαρύ. ταῦτα δὲ λέγεται κατὰ μεταφορὰν ἀπὸ τῶν ἁπτῶν· τὸ μὲν γὰρ ὀξὺ κινεῖ τὴν αἴσθησιν ἐν ὀλίγῳ 30 χρόνῳ ἐπὶ πολύ, τὸ δὲ βαρὺ ἐν πολλῷ ἐπ' ὀλίγον. οὐ δὴ ταχὺ τὸ ὀξύ, τὸ δὲ βαρὺ βραδύ, ἀλλὰ γίνεται τοῦ μὲν διὰ τὸ τάχος ἡ κίνησις τοιαύτη, τοῦ δὲ διὰ βραδυτητα. καὶ ἔοικεν ἀνάλογον ἔχειν τῷ περὶ τὴν ἁφὴν ὀξεῖ καὶ ἀμ-420 βλεῖ· τὸ μὲν γὰρ ὀξὺ οἷον κεντεῖ, τὸ δ ̓ ἀμβλὺ οἷον ὠθεῖ διὰ τὸ κινεῖν τὸ μὲν ἐν ὀλίγῳ, τὸ δὲ ἐν πολλῷ, ὥστε συμβαίνει τὸ μὲν ταχὺ τὸ δὲ βραδὺ εἶναι. περὶ μὲν οὖν ψόφου § 9 ταύτῃ διωρίσθω. ἡ δὲ φωνὴ ψόφος τίς ἐστιν ἐμψύχου· τῶν γὰρ ἀψύχων οὐθὲν φωνεῖ, ἀλλὰ καθ ̓ ὁμοιότητα λέγεται 24. καὶ τύπτον om. SUV. 420 3. συμ 31. ἐπ' om. SUVWy. ‖ οὐ δὴ] ὥστε οὐχὶ TW, ὥστε οὐδὲ F. βαίνειν ES. we hear or not if the ear continues to sound just like a horn: for the air contained within the ears [though undisturbed as we have seen by outer things] is moved perpetually with some peculiar movement of its own although the noise coming from outside is something external to the ear and not peculiar to it.) It is then on this account that it is said we hear by means of something void and resonant, because we hear by means of that which contains the air confined within it. Whether then, we may ask, is it the object striking or the object struck that makes the noise? May we reply that it is both, though each in a different manner? for sound is the movement of anything that can be moved in the same manner as those particles which bound off from smooth surfaces when struck. Everything however, as has been said, does not sound when striking and when struck: for example, a pin does not when struck by another pin: it is necessary that the thing struck should be smooth and even, so that the air may bound off and be agitated in a mass. The different qualities of sonorous objects are displayed in the actual sounds which they emit. For, just as colours are not visible without light, so in like manner it is impossible to distinguish the acute note and the grave independently of sound. These terms are applied metaphorically from the analogy of objects of touch, the acute or high note moving the sense to a great degree within a short space of time, the grave or low to a small degree within a large extent of time. Thus then it is not a correct account to say that the sharp is rapid or the heavy slow but the celerity of the action leads to a rapid movement in the one case, just as the tardiness leads to a slow movement in the other. And there does seem to be an analogy between these two forms of sound and the sharp and blunt as perceived by touch for the sharp pierces, as we may say, while the blunt, as it were, pushes, the one producing its movement in a short, the other in a large expanse of time, and thus as a result the one comes to be quick, the other to be slow. Thus much then on sound in general. Voice is the sound produced by an animate being: no inanimate object being said to speak except in virtue of the |
