A Text-Book of Experimental Psychology (Volume 1) - Tapa blanda

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This historic book may have numerous typos, missing text or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1911. Not illustrated. Excerpt: ... CHAPTER III ON AUDITORY SENSATIONS1 The Physical Basis of Pitch and Loudness.--In general, our auditory sensations are due to the occurrence of sound waves in the external air. These waves vary in length, in amplitude, and in form. Other things being equal, the shorter the wave length (i.e. the greater the vibration frequency) the higher in pitch will be the auditory sensation; and the greater the amplitude (i.e. the more distant the crest or trough of a wave from the position of equilibrium) the louder or more intense will be the auditory sensation. But these relations are only broadly true. For, as we shall see, the pitch and the loudness of our sensations do not always correspond to the wave length and the amplitude of the objective stimuli. [The Conduction of Sounds to the Inner Ear.--Sounds which are of moderate pitch and loudness are led to the inner ear by the membranes and ossicles of the middle ear. It has been experimentally shown that the ossicles vibrate with a frequency dependent on the vibration frequency of the sound stimulus, and that they must consequently be. regarded, not as a fixed conducting rod, but as a jointed, freely vibrating chain. If, however, the sounds be loud enough or be of sufficiently high pitch, they are audible to persons who through injury or disease have altogether lost this membranous and bony apparatus of the middle ear. It has been 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.] 1 The student is recommended to omit at his first reading those portions which...