====== Sound ======

When we consider the third kind of sense perception, namely hearing, we must state what the causes are by which the effects associated with it come about. In general terms let us lay it down that sound is the blow which is passed up to the soul through the ears by the air, brain and blood; and that the motion caused by the blow, beginning in the head and ending round the seat of the liver, is hearing. (Plato Timaeus 67A7-B5)