738 SPECIAL SENSES 



fundamental, which would produce errors and confusion in auditory 

 appreciation. The chain of bones, also, attached to the membrane acts as 

 a damper and prevents the persistence of vibrations after the waves of 

 sound cease in the air. This provision enables rapid successions of 

 sounds to be distinctly and accurately repeated. 



The arrangement of the muscles and bones of the middle ear is such 

 that the tension of the membrana tympani may be regulated and gradu- 

 ated with great nicety. It does not seem to be necessary to perfect 

 audition that this should be done for every single note or combination of 

 notes, but the membrane probably is brought by voluntary effort to a 

 definite degree of tension for notes within a certain range as regards 

 pitch or for successions and progressions of sounds in a particular key. 

 So far as the consciousness of this muscular action is concerned, it may 

 be revealed only by the fact of the correct appreciation of certain musi- 

 cal sounds. Some persons can educate the ear so as to acquire what is 

 called the faculty of absolute pitch ; that is, without the aid of a tuning- 

 fork or any musical instrument, they are able to recognize the exact 

 musical value of any given note. A possible explanation of this is that 

 such persons may have educated the muscles of the ear so as to put the 

 tympanic membrane in such a condition of tension as to respond to a 

 given note and to recognize the position of this note in the musical 

 scale. Finally, an accomplished musician, in conducting an orchestra, 

 can by a voluntary effort direct his attention to certain instruments and 

 hear their notes distinctly, separating them from the general volume of 

 sound, can distinguish discords and designate a single instrument making 

 a false note. 



Destruction of both tympanic membranes does not necessarily pro- 

 duce total deafness, although this condition involves considerable im- 

 pairment of hearing. So long as there is simple destruction of these 

 membranes, the bones of the middle ear and the other parts of the auditory 

 apparatus being intact, the waves of sound are conducted to the auditory 

 nerves, although this is done imperfectly. In a case reported by Astley 

 Cooper, one membrana tympani was entirely destroyed, and the other was 

 nearly gone, there being some parts of its periphery remaining. In this 

 person the hearing was somewhat impaired, although he could distin- 

 guish ordinary conversation without much difficulty. Fortunately, he 

 had considerable musical taste, and it was ascertained that his musical 

 ear was not seriously impaired ; " for he played well on the flute and 

 had frequently borne a part in a concert. I speak this, not from his 

 authority only, but also from that of his father, who is an excellent judge 

 of music, and plays well on the violin : he told me that his son, besides 

 playing on the flute, sang with much taste, and perfectly in tune." 



