Key Arguments

• He defines what has a sound as that which can move air that is 'one by continuity' and whose movement extends up to the hearing organ, thus making sonority a power to excite the medium towards the sense-organ.
• He asserts that the organ of hearing 'has connate air', and because the organ is itself in air, when the external air is moved, the internal air is moved, explaining why sound transmitted through air (and secondarily water) can affect the organ.
• He explains that the animal does not hear 'in every part' because air does not enter every part; only that part which contains air and is 'animate' is capable of being moved in the right way.
• He claims that air alone is 'soundless' because it is easily dispersed, but when its dispersion is prevented its movement is what sound is, and adds that the air inside the ears is 'walled in so as to be unmoving', in order to perceive in exact detail the differentiae of movement, making rest of the connate air a precondition for fine discrimination.
• He notes that we also hear in water because the water does not enter the connate air itself, nor even the ear, due to its spiral shape; when water does enter, or when the ear-drum is injured, there is no hearing, just as damage to the cornea destroys sight.
• He explains that the permanent echo-like resonance in the ear, 'like a horn', is no indication of hearing, since the air in the ears is always moving with its own proper movement, whereas true sound 'belongs to something else' and is not the connate air’s own movement.

Source Quotes

251 For then | 420 a 1 | at the same time it becomes one because of the surface, since the surface of a smooth object is one. What has a sound, then, is what can cause a movement in air that is one by continuity and that reaches up to the organ of hearing. But the organ of hearing has connate air.

What has a sound, then, is what can cause a movement in air that is one by continuity and that reaches up to the organ of hearing. But the organ of hearing has connate air. 252 And because this organ is in air, when the air outside is moved, the air inside is moved. That is why the animal | 420 a 5 | does not hear in every part of it, nor does the air enter every part.

252 And because this organ is in air, when the air outside is moved, the air inside is moved. That is why the animal | 420 a 5 | does not hear in every part of it, nor does the air enter every part. For it is not in every part that it has air, but the part that is going to be moved and is animate. 253 The air alone, then, is soundless because it is easily dispersed; but when it is prevented from being dispersed, its movement is sound. The air inside the ears, though, has been walled in so as to be unmoving, in order that it may perceive in exact detail all the differentiae (diaphora) | 420 a 10 | of movement.

For it is not in every part that it has air, but the part that is going to be moved and is animate. 253 The air alone, then, is soundless because it is easily dispersed; but when it is prevented from being dispersed, its movement is sound. The air inside the ears, though, has been walled in so as to be unmoving, in order that it may perceive in exact detail all the differentiae (diaphora) | 420 a 10 | of movement.

253 The air alone, then, is soundless because it is easily dispersed; but when it is prevented from being dispersed, its movement is sound. The air inside the ears, though, has been walled in so as to be unmoving, in order that it may perceive in exact detail all the differentiae (diaphora) | 420 a 10 | of movement. 254 That is why we hear also in water, because the water does not enter the connate air itself. On the contrary, it does not even enter the ear itself, because of its spiral shape.

The air inside the ears, though, has been walled in so as to be unmoving, in order that it may perceive in exact detail all the differentiae (diaphora) | 420 a 10 | of movement. 254 That is why we hear also in water, because the water does not enter the connate air itself. On the contrary, it does not even enter the ear itself, because of its spiral shape. When this does happen, there is no hearing. Nor is there if the ear drum is injured, just as with the cornea of the eye. But it is no indication of whether we hear or not that the | 420 a 15 | ear always has an echo, like a horn.

Key Concepts

• What has a sound, then, is what can cause a movement in air that is one by continuity and that reaches up to the organ of hearing.
• But the organ of hearing has connate air. 252 And because this organ is in air, when the air outside is moved, the air inside is moved.
• That is why the animal | 420 a 5 | does not hear in every part of it, nor does the air enter every part. For it is not in every part that it has air, but the part that is going to be moved and is animate. 253
• The air alone, then, is soundless because it is easily dispersed; but when it is prevented from being dispersed, its movement is sound.
• The air inside the ears, though, has been walled in so as to be unmoving, in order that it may perceive in exact detail all the differentiae (diaphora) | 420 a 10 | of movement. 254
• That is why we hear also in water, because the water does not enter the connate air itself. On the contrary, it does not even enter the ear itself, because of its spiral shape. When this does happen, there is no hearing. Nor is there if the ear drum is injured, just as with the cornea of the eye.

Context

II.8 (end of 419b–420a15), where Aristotle gives a hylomorphic and physiological account of the organ of hearing, emphasizing the role of confined 'connate air' and the structural features of the ear for the reception of sound.