SEC. 5. ON AUDITORY PERCEPTIONS AND 



JUDGMENTS. 



853. In spite of the many and striking differences between 

 the two senses, it is possible to draw several parallels between 

 auditory and visual sensations. When we are the subject of a 

 visual sensation we refer the cause not to changes taking place in 

 the retina, but to some luminous object in the external world. So 

 also, when we are the subject of an auditory sensation we refer the 

 cause not to changes taking place in the internal ear, but to some 

 sounding body outside the ear and in the vast majority of cases to 

 some sounding body outside ourselves. We do not simply feel 

 auditory sensations, we perceive sounds, cf. 779. 



We have seen that in the case of the eye, visual sensations, 

 excited by events taking place in the visual apparatus itself, may 

 be confounded with sensations excited by objects in the external 

 world ; and much the same happens with the ear also. The tympanic 

 membrane for instance may be thrown into vibrations not by waves 

 of sound, but by objects coming mechanically into contact with 

 it ; particles of the dried secretion of the external auditory passage, 

 the ' wax of the ear,' playing on the tympanic membrane, may give 

 rise to auditory sensations, a ' buzzing ' or ' singing in the ears,' 

 which we cannot by the mere psychological examination of the 

 sensations themselves distinguish from auditory sensations excited 

 in the ordinary way by sonorous vibrations reaching us from some 

 sounding body at a distance. And in a general way, we may 

 speak of entotic phenomena, corresponding to the entoptic pheno- 

 mena on which we dwelt ( 736) in speaking of vision. 



Auditory sensations moreover may arise, in the complete 

 quiescence of the tympanic apparatus and perilymph, as the 

 result of changes either in the auditory epithelium or in the 

 central auditory nervous apparatus. We may be subject to audi- 

 tory phantoms or hallucinations, corresponding to ocular phantoms 

 or hallucinations, and like them often misleading or distressing. 

 Few persons, moreover, can listen to exciting music or can hear 



F. 



