1892.] On the Audibility of single Sound Waves, Sfc. 319 



ihoroughly convinced that a single contraction produced by a single 

 induction shock gave rise to an audible sound of somewhat the same 

 character as the first sound of the heart.* 



But it was urged by some physical friends that if the contraction 

 were really a single one, causing a single vibration, it could not be 

 heard, because a series of vibrations was necessary to produce a sound, 

 and therefore, unless secondary oscillations succeeded the contraction, 

 the latter would be inaudible. 



Now muscular tissue, especially when surrounded by fascia, 

 fat, &c., seemed to be particularly ill suited for sustaining any such 

 series of vibrations, and no such oscillations can be detected on the 

 graphic record of the muscular movement. 



When the muscle was stimulated at regular intervals with increasing 

 frequencies the short thuds due to each contraction could be heard 

 separately up to a rate of about forty per second, when these thuds 

 became gradually fused into a dull tone, only clear at somewhat 

 above the rate now accepted as the lower limit of audibility of true 

 tones, viz., forty-one vibrations per second. We adopt this rate, 

 given by Helmholtz,t and neglect the rates of Savart and Preyer,J 

 as we believe the tones they heard were probably due to harmonic 

 additions to the rumble of single sound waves caused by 8 or 

 15 V.D. per second. That the droning sound produced by the 

 lowest organ pipes is not really heard as a true tone seems satis- 

 factorily proved by the well-known fact that they cannot be tuned 

 by the ear alone even of the greatest expert, but only indirectly by 

 the beats which they make with the tones of the upper octaves. The 

 value of such sounds as those produced by a body vibrating slower 

 than forty times per second, and having no true tone capable of 

 differentiation of pitch, can only be to modify and soften the tones of 

 higher octaves, which so occupy the auditory apparatus as to make 

 the separation of the slow single vibrations no longer perceptible. 



But the question of the vibrations becoming fused into a musical 

 tone is distinct from that of the audibility of each vibration separately, 

 except in so far as the admission of imperfect union distinctly 

 implies the audibility of the separate vibrations. 



To us there did not seem to be the least physiological difficulty in 



* ' Journal of Physiology,' vol. 6, p. 287. 



f ' Die Lehre v. d. Tonempfindungen,' &c., Braunschweig, 1870, p. 278 : " In der 

 kunstlerischt vollendeten Musik des Orchesters ist deshalb auch der tiefste Ton 

 welcher angewendet wird, das E, des Contrabasses von 41 Schwingungen, und ich 

 glaube mit Sicherheit voraussagen zu konnen, das alle Anstrengunen der neueren 

 Technik, tiefere gut musikalische Tone hervorzubringen, scheitern mussen, nicht 

 weil ea an Mitteln fehlte. passende Luftbewegungen zu erregen, sondern weil das 

 menschlicne Ohr seine Dienste versagt." 



J ' Physiologisclie Abhandlungen,' Theil 1, pp. 1 17. 



z 2 



