W. Ogle[6] has been so kind as to search
the best recent authorities on the functions of the eustachian tube,
and he informs me that it is almost conclusively proved that it remains
closed except during the act of deglutition; and that in persons
in whom the tube remains abnormally open, the sense of hearing,
as far as external sounds are concerned, is by no means improved;
on the contrary, it is impaired by the respiratory sounds being
rendered more distinct. If a watch be placed within the mouth,
but not allowed to touch the sides, the ticking is heard much less
plainly than when held outside. In persons in whom from disease
or a cold the eustachian tube is permanently or temporarily closed,
the sense of hearing is injured; but this may be accounted for by mucus
accumulating within the tube, and the consequent exclusion of air.
We may therefore infer that the mouth is not kept open under the sense
of astonishment for the sake of hearing sounds more distinctly;
notwithstanding that most deaf people keep their mouths open.
[4] Mecanisme de la Physionomie,' Album, p. 6.
[5] See, for instance, Dr. Piderit (`Mimik und Physiognomik,' s.
Pages:
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416