§2.8#1Νῦν δὲ πρῶτον περὶ ψόφου καὶ ἀκοῆς διορίσωμεν.
Now let us first make determinations concerning sound and hearing.
ἔστι δὲ διττὸς ὁ ψόφος· ὁ μὲν γὰρ ἐνεργείᾳ τις, ὁ δὲ δυνάμει·
Sound is double; for one is actual, and the other potential.
τὰ μὲν γὰρ οὔ φαμεν ἔχειν ψόφον, οἷον σπόγγον, ἔρια, τὰ δʼ ἔχειν, οἶον χαλκὸν καὶ ὅσα στερεὰ καὶ λεῖα, ὅτι δύναται ψοφῆσαι, τοῦτο δʼ ἐστὶν αὐτοῦ μεταξὺ καὶ τῆς ἀκοῆς ἐμποιῆσαι ψόφον ἐνεργείᾳ.
For some things we say do not have sound, such as sponge and wool, but others do, such as bronze and whatever is solid and smooth, because they are capable of sounding, and this is to be capable of producing actual sound in the intermediate space between itself and the hearing.
γίνεται δʼ ὁ κατʼ ἐνέργειαν ψόφος ἀεί τινος πρός τι καὶ ἔν τινι· πληγὴ γάρ ἐστιν ἡ ποιοῦσα.
And actual sound comes about always of something against something and in something; for it is a blow that produces it.
διὸ καὶ ἀδύνατον ἑνὸς ὄντος γενέσθαι ψόφον· ἕτερον γὰρ τὸ τύπτον καὶ τὸ τυπτόμενον· ὥστε τὸ ψοφοῦν πρός τι ψοφεῖ· πληγὴ δʼ οὐ γίνεται ἄνευ φορᾶς.
Wherefore also it is impossible for sound to come about when there is only one thing; for that which strikes and that which is struck are different; so that what sounds, sounds against something; and a blow does not come about without movement.
ὥσπερ δʼ εἴπομεν, οὐ τῶν τυχόντων πληγὴ ὁ ψόφος· οὐθένα γὰρ ποιεῖ ψόφον ἔρια ἂν πληγῇ, ἀλλὰ χαλκὸς καὶ ὅσα λεῖα καὶ κοῖλα· ὁ μὲν χαλκός, ὅτι λεῖος, τὰ δὲ κοῖλα τῇ ἀνακλάσει πολλὰς ποιεῖ πληγὰς μετὰ τὴν πρώτην, ἀδυνατοῦντος ἐξελθεῖν τοῦ κινηθέντος.
And as we said, sound is not the blow of just any things; for wool produces no sound if it is struck, but bronze and whatever is smooth and hollow do; bronze because it is smooth, and hollow things by reflection produce many blows after the first, since that which is set in motion is unable to escape.
ἔτι ἀκούεται ἐν ἀέρι, κἀν ὕδατι, ἀλλʼ ἧττον, οὐκ ἔστι δὲ ψόφου κύριος ὁ ἀὴρ οὐδὲ τὸ ὕδωρ, ἀλλὰ δεῖ στερεῶν πληγὴν γενέσθαι πρὸς ἄλληλα καὶ πρὸς τὸν ἀέρα.
Furthermore, sound is heard in air, and in water, but less so; but neither air nor water is the primary cause of sound, but there must be a blow of solid things against each other and against the air.
τοῦτο δὲ γίνεται ὅταν ὑπομένῃ πληγεὶς ὁ ἀὴρ καὶ μὴ διαχυθῇ.
And this comes about when the air, being struck, remains and is not dispersed.
διὸ ἐὰν ταχέως καὶ σφοδρῶς πληγῇ, ψοφεῖ· δεῖ γὰρ φθάσαι τὴν κίνησιν τοῦ ῥαπίζοντος τὴν θρύψιν τοῦ ἀέρος, ὥσπερ ἂν εἰ σωρὸν ἢ ὁρμαθὸν ψάμμου τύπτοι τι φερόμενον ταχύ.
Therefore, if it is struck quickly and violently, it sounds; for the movement of that which strikes must anticipate the dispersing of the air, just as if one were to strike a heap or a line of sand while moving rapidly.
ἠχὼ δὲ γίνεται ὅταν, ἀέρος ἑνὸς γενομένου διὰ τὸ ἀγγεῖον τὸ διορίσαν καὶ κωλῦσαν θρυφθῆναι, πάλιν ὁ ἀὴρ ἀπωσθῇ, ὥσπερ σφαῖρα.
And an echo comes about when, the air having become one because of the vessel which defined it and prevented it from being dispersed, the air is pushed back again, like a ball.
ἔοικε δʼ ἀεὶ γίνεσθαι ἠχώ, ἀλλʼ οὐ σαφής, ἐπεὶ συμβαίνει γε ἐπὶ τοῦ ψόφου καθάπερ καὶ ἐπὶ τοῦ φωτός· καὶ γὰρ τὸ φῶς ἀεὶ ἀνακλᾶται (οὐδὲ γὰρ ἂν ἐγίνετο πάντῃ φῶς, ἀλλὰ σκότος ἔξω τοῦ ἡλιουμένου), ἀλλʼ οὐχ οὕτως ἀνακλᾶται ὥσπερ ἀφʼ ὕδατος ἢ χαλκοῦ ἢ καί τινος ἄλλου τῶν λείων, ὥστε σκιὰν ποιεῖν, ᾗ τὸ φῶς ὁρίζομεν.
And it seems that an echo always comes about, but not clearly, since the same thing happens with sound as with light; for light also is always reflected (for otherwise light would not have come about everywhere, but there would be darkness outside the area shone upon by the sun), but it is not reflected in the same way as from water or bronze or any other of the smooth things, so as to make a shadow, by which we define light.
τὸ δὲ κενὸν ὀρθῶς λέγεται κύριον τοῦ ἀκούειν.
And the void is rightly said to be the primary cause of hearing.
δοκεῖ γὰρ εἶναι κενὸν ὁ ἀήρ, οὗτος δʼ ἐστὶν ὁ ποιῶν ἀκούειν, ὅταν κινηθῇ συνεχὴς καὶ εἷς.
For the air seems to be void, and this is what makes us hear, when it is set in motion as continuous and one.
ἀλλὰ διὰ τὸ ψαθυρὸς εἶναι οὐ γεγωνεῖ, ἂν μὴ λεῖον ᾗ τὸ πληγέν.
But because it is easily dispersed, it does not make a distinct sound, unless that which is struck is smooth.
τότε δὲ εἶς γίνεται ἅμα διὰ τὸ ἐπίπεδον· ἓν γὰρ τὸ τοῦ λείου ἐπίπεδον.
But then it becomes one at the same time because of the flat surface; for the flat surface of that which is smooth is one.
ψοφητικὸν μὲν οὖν τὸ κινητικὸν ἑνὸς ἀέρος συνεχείᾳ μέχρις ἀκοῆς.
That which is capable of sounding, then, is that which is capable of setting in motion a single continuous air as far as the hearing.
ἀκοῇ δὲ συμφυὴς ἀήρ· διὰ δὲ τὸ ἐν ἀέρι εἶναι, κινουμένου τοῦ ἔξω ὁ εἴσω κινεῖται.
And air is connate with hearing; and because hearing is in air, when the outer air is set in motion, the inner air is set in motion.
διόπερ οὐ πάντῃ τὸ ζῷον ἀκούει, οὐδὲ πάντῃ διέρχεται ὁ ἀήρ· οὐ γὰρ πάντῃ ἔχει ἀέρα τὸ κινησόμενον μέρος καὶ ἔμψοφον.
Therefore the animal does not hear in every part, nor does the air pass through every part; for the part that is to be set in motion and contains sound does not have air everywhere.
αὐτὸς μὲν δὴ ἄψοφον ὁ ἀὴρ διὰ τὸ εὔθρυπτον· ὅταν δὲ κωλυθῇ θρύπτεσθαι, ἡ τούτου κίνησις ψόφος.
The air itself indeed is soundless because it is easily dispersed; but when it is prevented from being dispersed, its motion is sound.
ὁ δʼ ἐν τοῖς ὠσὶν ἐγκατῳκοδόμηται πρὸς τὸ ἀκίνητος εἶναι, ὅπως ἀκριβῶς αἰσθάνηται πάσας τὰς διαφορὰς τῆς κινήσεως.
And the air in the ears has been built in so as to be motionless, in order that it may accurately perceive all the differences of movement.
διὰ ταῦτα δὲ καὶ ἐν ὕδατι ἀκούομεν, ὅτι οὐκ εἰσέρχεται πρὸς αὐτὸν τὸν συμφυῆ ἀέρα· ἀλλ᾿ οὐδʼ εἰς τὸ οὖς, διὰ τὰς ἕλικας.
And for these reasons we hear also in water, because water does not enter as far as the connate air itself; and not even into the ear, because of the spiral passages.
ὅταν δὲ τοῦτο συμβῇ, οὐκ ἀκούει· οὐδʼ ἂν ἡ μῆνιγξ κάμῃ, ὥσπερ τὸ ἐπὶ τῇ κόρῃ δέρμα.
But whenever this happens, the animal does not hear; nor does it hear if the membrane is diseased, just as the skin over the pupil.
ἀλλὰ καὶ σημεῖον τοῦ ἀκούειν ἢ μὴ τὸ ἠχεῖν ἀεὶ τὸ οὖς ὥσπερ τὸ κέρας· ἀεὶ γὰρ οἰκείαν τινὰ κίνησιν ὁ ἀὴρ κινεῖται ὁ ἐν τοῖς ὠσίν· ἀλλʼ ὁ ψόφος ἀλλότριος καὶ οὐκ ἴδιος.
But also a sign of whether one hears or not is that the ear is always ringing like a horn; for the air in the ears is always moving with a certain proper motion of its own; but the sound is foreign and not its own.
καὶ διὰ τοῦτό φασιν ἀκούειν τῷ κενῷ καὶ ἠχοῦντι, ὅτι ἀκούομεν τῷ ἔχοντι ὡρισμένον τὸν ἀέρα.
And because of this they say we hear by the void and ringing, because we hear by that which contains the defined air.
πότερον δὲ ψοφεῖ τὸ τυπτόμενον ἢ τὸ τύπτον;
But whether is it that which is struck that sounds, or that which strikes?