Volume 1
A text-book of experimental psychology : with laboratory exercises / by Charles S. Myers.
- Charles Samuel Myers
- Date:
- 1911
Licence: Public Domain Mark
Credit: A text-book of experimental psychology : with laboratory exercises / by Charles S. Myers. Source: Wellcome Collection.
40/370 page 20
![demonstrated that high or very loud sounds are directly communicable from the air to the inner ear by way of the bony walls of the skull. Under normal as well as under abnormal conditions of health, there can be little doubt about the occurrence of such direct bone conduction in the case of high or very loud sounds.] \TZie Conduction of Sounds from Ear to Ear.—Direct bone conduction also occurs when a sounding instrument, e.g. a tuning-fork, is brought in contact with the head or teeth (exp. 15). It is likewise a factor of considerable psychological importance when a sound is led to one ear only (exp. 16); for unless the sound be low in pitch and intensity, it travels to the opposite ear, partly perhaps by way of the two Eustachian tubes across the pharynx, but chiefly over the bony vault and across the base of the skull. For this reason we are practically unable to excite the auditory end organs of one side of the body without simultaneously exciting (of course, in less degree) the corresponding organs of the opposite side,—an experimental difficulty which it is most important to bear in mind.] The Physical Basis of Timbre.—We have seen that the pitch and the loudness of sensations of sound are closely connected with wave length and amplitude, but we have yet to examine a feature in which sound waves further differ from one another, namely, variety of form. The vibrations of a sound wave, if wholly devoid of regularity, are termed ‘ non-periodic/ They are termed ‘ periodic ’ when during equal periods of time, however long, the same movements are repeated, however complex. Further, periodic vibrations are classified as ‘pendular' and ‘ non-pendular/ Pendular vibrations produce a particular form of sound wave, the ‘sine wave,' which is important because theoretically it gives rise to the purest sensation of a single tone1. All 1 This form of sound wave is called the ‘ sine wave ’ because at any instant the displacement of any particle from its position of equilibrium is proportional to the sme of an angle, which in turn is proportional to the distance of that particle from the rear of the wave. Within the length of a wave this angle increases from f o ’ to 27r.](https://iiif.wellcomecollection.org/image/b3135984x_0001_0040.jp2/full/800%2C/0/default.jpg)
