On a modification of the Helmholtz theory of hearing / by Albert A. Gray, M.D.

  • Albert Alexander Gray
Date:
[1900?]
Catalogue details

Licence: In copyright

Credit: On a modification of the Helmholtz theory of hearing / by Albert A. Gray, M.D. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    Helmholtz looked upon each transverse fibre of the basilar membrane to be tuned to a particular tone and no other, so that when that tone, either' by itself or in conjunction with other tones, is transmitted to the fluid in the labyrinth, the fibre (possibly also one or two adjacent ones) is set in sym- pathetic vibration. The nerve-fibre which is in contact with the hair-cell corresponding to that fibre, will thus be stimulated, and, the stimulus being carried to the brain, we are conscious of the existence of that particular tone. When the tone is a com- pound one, therefore, those fibres of the basilar membrane which are in sympathy with the several simple tones of which the compound tone is composed, will be set in vibration, and we become conscious of the co-existence of several simple tones of different pitch. This theory in some respects suits the facts of the case very well. It is in keeping with the gradual decrease which the fibres of the basilar membrane undergo in length from apex to base. It is, further, in keeping with the increase in size and strength of the ligamentum spirale downwards, as described at the beginning of this paper, though unknown when Helmholtz put forth his theory. For obviously, as the fibres become shortened and more tense towards the base of the cochlea, their vibration - frequency becomes increased. Helmholtz's theory also explains the fact, which has been discovered by pathological and clinical examination, that when the lower turns of the cochlea are affected by disease the hearing for the higher musical notes is lost. To the acceptance of Helmholtz's theory as it stands there appears to the writer to be some very serious objections; indeed, unless they are explained these are fatal to the theory. Amongst other objections which have occurred to the writer are these:—The existence of noise as distinguished from musical sounds; the fact that the ear is, under certain circumstances, able to appreciate difference of phase. Helmholtz appears to have been, to a certain extent at least, aware of these difficulties, for he tried to explain the first in ;i way which we now know to be inadmissible, and he denied the truth of the second altogether, whereas we know now that the ear does appreciate phase under certain, circumstances.
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