Abstracts of Technical Articles From Bell System Sources (01 April 1929)

Quently, copious references to the experimental results of other workers have been included. The material is grouped under four headings: (1) Speech, (2) Music and Noise, (3) Hearing, and (4) Perception of Speech and Hearing. The first part is concerned with the mechanism of speaking, the classification of the fundamental English speech sounds, and with the wave forms of such sounds. It includes a description of various types of apparatus which can be used for making permanent records of speech waves and gives a large number of accurate wave pictures of the speech sounds together with the power contained in such waves.

In the second part similar data are given for musical sounds and noise. The third part begins with a discussion of a theory of hearing which is proposed to explain the experimental facts of audition. This is followed by a discussion of the known facts of audition such as the limits of audition, the minimum perceptible differences in sound, masking effects, binaural effects, methods of testing the acuity of hearing, etc. 

Along with this discussion is given a description of the apparatus and experimental methods used for determining these facts. The fourth part is concerned with those phases of the subject that involve personal judgment, that is, the psychological element. A scale for measuring the loudness and the pitch of complex sounds is defined. Experimental d a t a are given which show how these two subjective quantities depend upon external physical quantities.