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A NEW THEOEY OF HEAKING. 



By C. Herbert Hurst, Ph.D. 



With Plate XX. 



[Read December 14th, 1894.] 



Inteoduction. 



Kohleausch's experiments described in Wiedemann's 

 Annalen (Vol. X.), amongst others, show that two air- 

 waves separated by a suitable interval of time suffice for 

 the production of a distinct tone-sensation, the pitch 

 being determinable by the ear within the limits of error 

 expressed by the ratio 24:25. Increase of the absolute 

 number of vibrations with the same time-intervals narrows 

 the limits of error in determining the pitch by the ear, 

 till the absolute number reaches 16, beyond which point 

 a further increase does not appreciably facilitate the 

 determination. 



These results, and especially the first one, disprove, 

 not only all existing theories of hearing based on assump- 

 tions as to " resonance " or response of sense-hairs, fibres 

 of basilar membrane, or any parts of the organ " tuned " 

 to the same pitch as the sound, but equally disproves all 

 new resonance-theories of hearing which may ever be 

 propounded in the future. 



Limits of space forbid me here to repeat a description 

 of the ear and especially of the cochlea. The description 

 given by Professor Schiifer in Quain's Anatomy (10th 

 edition) is accessible to all, and I have taken that descrip- 

 tion as correct except in that I have considered both edges 

 of the tectorial membrane to be attached, the outer edge 

 being, not free, but attached to the upper surface of tbe 

 cells of Hensen, The measurements given (op. cit., vol. 



