A. KHARKEVICH, Electroacoustic Equipment, Energoizdat, 1933, 256 pp., price 4 rubles.

The author set himself the task of providing an introductory course in electroacoustics, intended for engineers and students who wish to find their bearings in the basic questions of the theory, calculation, and design of electroacoustic equipment. The range of questions is limited to general electroacoustic equipment, by which are meant: 1) loudspeakers, 2) microphones, and 3) sound-measuring or recording devices. Three chapters devoted to these questions are preceded by an introductory chapter on physiological and musical acoustics and on the basic questions of the theory of electroacoustic processes. From the beginning to the end of the book the exposition is conducted on the basis of a rigorously thought-out system of electroacoustic analogies, which greatly facilitates understanding of complex processes in various apparatus. The exposition is concise, without excessive derivations, but at the same time quite rigorous and clear. The book is easy and interesting to read. The descriptive material is taken from the latest foreign literature and is supplemented, on the basis of the author’s experience (he is one of the prominent workers in our industry), with data on apparatus of Soviet manufacture. The book is not cluttered with minor details and superfluous figures, so that the reader’s attention is concentrated on the basic ideas of the designs. The rare combination in the author of an engineer with rich practical experience, excellent training in physics, and an outstanding teacher has enabled him to create an exceptionally successful book.

A. Kharkevich’s book may be recommended reading for every physicist interested in oscillatory processes and, in particular, in electroacoustics, but above all it is an excellent textbook for all higher educational institutions where a course in introductory electroacoustics is taught. Considering that until now there have been no suitable textbooks on electroacoustics in Russian, it should be noted that the author has filled a substantial gap in the physico-technical literature. The book is supplied with a comprehensive bibliographical index. Among its shortcomings the following should be noted: 1) there are no problems, examples, or review questions; 2) gramophone technology is little touched upon (although the gramophone is not an electroacoustic device in the literal sense of the word, technically it is closely related to the questions under discussion, and its inclusion would have been quite natural and very desirable); 3) adjustment processes in electroacoustic equipment are not touched upon (as the author himself points out).

Among the errors I shall note the following: on pp. 19 and 20 the instrument “bass trumpet” and “bass-trumpet” is mentioned; this is probably a translation of the name of the instrument known among us as the “bass tuba.” The loudness range of speech at a distance of 100 decibels (p. 30) is clearly overstated—it is at most 60 db (from 25 to 85 db). It is also stated there that the voice is 20,000 times

weaker than an orchestra—should be considered no more than 100–200 times. On p. 49, in equations (21) and (22), the minus sign before the expressions should be changed to a plus. In Fig. 2, p. 40, a very unfortunate variable scale of the abscissa was chosen. On p. 60, line 19 from the bottom, an increase at resonance by a factor of two is erroneously indicated, which does not correspond to Fig. 10. On p. 42, the question of increasing loudness is presented somewhat confusedly.

We permit ourselves to hope that the author will eliminate all these minor shortcomings in the second edition, which should be prepared without delay, since the print run of the first edition—4,000 copies—is obviously too small. One would like to see the second edition better designed. The ordinary appearance of the first edition does not attract the reader’s eye, whereas the book deserves to be published better and more elegantly.

S. Rzhevkin.