GENERATION OF ANIMALS, V. vii. 



deep " voice, others a high-pitched voice, others a 

 well-pitched voice, suitably proportionate between 

 the two extremes ; some, too, have big voices, others 

 small ones ; also they differ in respect of being 

 smooth, or rough, flexible and inflexible. So we 

 must consider what are the causes to which each of 

 these is due. With regard to the pitch, the same 

 cause is to be held responsible as that which controls 

 the change which they undergo in passing from 

 youth to age. All animals when younger have a 

 higher voice, except calves, which have a deeper one. 

 The same occurs as between male and female as 

 well : in all animals (except cattle) the female has a 

 higher voice than the male, and this is especially 

 noticeable in human beings, for Nature has given 

 them this faculty in an exceptional degree because 

 they alone among the animals use the voice for 

 rational speech, of which the voice is the " material." 

 In cattle the reverse obtains : cows have a deeper 

 voice than bulls. We have explained partly in the 

 treatise Of Sensation.^ partly in that Of the SoiilS for 

 what purpose animals have a voice, and what " voice " 

 is, and generally what sound is. But since deepness 

 of pitch consists in the movement being slow, and 

 height of pitch in its being fast, the question is 

 whether the speed is caused by that which initiates 

 or that which experiences the movement, and this 

 is somewhat puzzling. Some people hold that the 

 movement of a large voliune is slow and that of a 

 small volume fast, and that this is the cause why some 

 animals have deep voices and others high ones. Up 

 to a point this statement is satisfactory^ but not 

 completely so. It is, of course, correct to say that, 



' See 419 b 3—420 b 23. 



543 



