Prof. A. M. Mayer's Researches in Acoustics. 451 



If it be true that when simple vibrations impinge on the ear 

 the tympanic and basilar membranes vibrate twice while the co- 

 vibrating body only vibrates once, then it follows that, if the 

 same simple vibrations can be sent directly to the covibrating 

 parts of the ear without the intervention of the basilar mem- 

 brane, we should perceive a sound which is the octave of the one 

 we experienced when the same simple vibrations entered the ear 

 through the tympanic membrane. Hence it appears that our 

 hypothesis can be brought to the test of experiment in the fol- 

 lowing manner : — A tuning-fork held near the ear causes a 

 sensation corresponding to the designated pitch of the fork. 

 But the vibrations of this fork can be sent to the inner ear 

 through the bones of the head ; and although we cannot prevent 

 the simultaneous vibration of the tympanic and basilar mem- 

 branes, yet we can at the same time directly vibrate the parts of 

 the inner ear. Therefore, if we first hold this fork near the ear 

 and note its pitch and the quality of its sound and then press 

 its foot firmly against the temporal bone, we should perceive a 

 marked difference in the timbre of the fork when sounded in 

 these two different positions ; for when its foot is against the 

 head, we should hear the usual simple sound of the fork accom- 

 panied by its octave. 



Thus, if we take an Ut 3 fork and vibrate it near the ear and 

 closely apprehend the character of its sound, we shall experience 

 a sensation which certainly does not contain that corresponding 

 to the higher octave of the fork. Now press firmly the foot of 

 the fork against the zygomatic process close to the ear, directing 

 the foot of the fork somewhat backward, and we shall distinctly 

 hear the higher octave of the fork singing in concert with its 

 real note. If the auditory canal be now closed by gently placing 

 the tip of the finger over it, we shall perceive the higher octave 

 with an intensity almost equal to that of the fundamental note. 

 The same sensation, though less intense, may be obtained by 

 placing the fork on any part of the temporal bone. One can 

 also perceive distinctly the higher octave when the fork is placed 

 on the parietal bone, about two inches in front and an inch or 

 so to the side of the foramen, with its foot directed toward the 

 opposite inner ear, while the auditory canal of this ear is gently 

 closed with the tip of the finger. But the higher octave sings 

 out with the greatest intensity when the foot of the fork is placed 

 on the tragus of the outer ear. A friend, who is a musician as 

 well as a physicist, repeated these experiments ; and he informs 

 me that when the foot of the fork is placed against the tragus of 

 his ear he hears the higher octave to the almost entire exclusion 

 of the lower, and with a clearness that reminds him of the sen- 

 sation perceived when an Ut 4 resonator, placed to the ear, rein- 



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