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

  • Gray, Albert A. (Albert Alexander), 1868-1936.
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.

    13/32 (page 333)
    with the same note, but with an amplitude less than BB, and so on, until at, say, EE, the amplitude of movement of the fibre will be so small as to be negligible. In the same way, if we proceed down the basilar membrane, the fibre CC, being a minute amount shorter, and subject to tension a minute amount greater than AA, will vibrate in sym- pathy with the note, but with an amplitude less than A A. So also the fibre at GG- will vibrate in sympathy with the note, but with less amplitude than CC, and so on until at FF the vibra- tions are so small as to be negligible. It must be added that this is not a matter of conjecture, but is strictly in accord with the laws of sympathetic resonance. Suppose now that we make a longitudinal section through the basilar membrane when the same note was being sounded, we should find that, at the end of one phase of the wave, it was A D i i 1 i i • • • i i J E i 1 1 i i i ■ i i j i ■ • o Fig. 3. raised from its position of rest and had become bent, the bend being of course at the point where the fibre AA was cut trans- versely, as in fig. 3. At the end of the opposite phase of the wave the bend would occur at a point exactly opposite. The whole amplitude of the movement of the fibre A would therefore be represented by the line AO, that of the fibre B by the line BK, and so on, until at the points E and F the fibres, having a vibration-frequency so far removed from the note, would move to an extent so small as to be negligible. When the fibres move as described, then the hair-cells attached to their inner extremities would be carried along with them; so that in the movement upwards the hairs of the hair-cells