MEMBRANA TYMPANI. 207 



tivelj feeble. In following with the ear any piece of music, 

 reasoning from purely physical considerations, it must at 

 times occur that the tones are in exact unison or in harmony 

 with the fundamental tone of the membrana tympani. Sup- 

 posing the fundamental tone of the membrane to be constant 

 and invariable, such tones would be heard much more dis- 

 tinctly than others, as a physical necessity. Such a difference 

 in the appreciation of certain notes in melody does not oc- 

 cur ; and the only reasonable explanation of this is that the 

 tension of the membrane is altered. It is shown by anatomi- 

 cal researches that the tension can be altered by muscular 

 action, and, as the muscles are striated, we may suppose that 

 it may be modified rapidly. Physiological observations show 

 that such modifications in tension do occur; and there are 

 on record unquestionable instances in which the membrana 

 tympani is tightened by a voluntary contraction of the ten- 

 sor-tympani muscle. 1 



Another important point to note in this connection is the 

 following : Can it be shown that the appreciation of the pitch 

 of tones bears any relation to the degree of tension of the 

 tympanic membrane ? We can answer this question unre- 

 servedly in the affirmative. When the membrane is ren- 

 dered tense, there is insensibility to low tones. "When the 

 membrane is brought to the highest degree of tension by 

 voluntary contraction of the tensor tympani, the limit of ap- 

 preciation of high tones may be raised from three thousand 

 to five thousand vibrations. It is a fact in the physics of the 

 membrana tympani, that the vibrations are more intense the 

 nearer the membrane approaches to a vertical position. It 

 has also been shown that the membrane has a strikingly ver- 

 tical position in musicians, and that the position is very 

 oblique in persons with an imperfect musical ear. 8 This fact 

 has a most important bearing on the probable relation be- 

 tween the membrana tympani and the correct appreciation 

 of musical sounds. 



1 See page 201. 2 TROLTSCH, Diseases of the Ear y New York, 1869, p. 36. 

 144 



