Prof. S. Ya. LIFSHITS. Course in Architectural Acoustics. Published by MVTU, Moscow. 1927. 128 pp. Price 2 rubles.

Architectural acoustics, one of the young branches of technical acoustics, received systematic development only in the twentieth century, chiefly thanks to the work of the American physicist Wallace Sabine (W. C. Sabine, Collected Papers on Acoustics, 1922). S. Ya. Lifshits is, in our country, a pioneer in the field of architectural acoustics. Having understood the importance of the question for modern technology and having successfully resolved a number of difficult experimental problems, he brought to completion, under our conditions, the difficult work of practical investigation and evaluation of rooms from the acoustical point of view. The author’s work on the investigation of the acoustical data of the principal Moscow theaters and concert halls, as well as his theory of the optimum reverberation (loudness), are a valuable contribution to science and are constantly cited in the literature (see, for example, Handbuch der Physik, Vol. VIII, 1927 ed.). In the published course of lectures, delivered by the author at the Construction Faculty of the Higher Technical School and at VKhUTEMAS, S. Ya. Lifshits has collected and systematized rich material, using the latest literary data and his own experience.

The book is divided into three parts. The first part contains general information from the theory of sound and is very elementary and brief in scope. There is no doubt that the first part of the book is a wholly insufficient introduction to architectural acoustics, not providing a good physical and mathematical basis for the serious material presented further on. The second part deals with the acoustics of theaters, concert halls, and auditoriums. Here the laws of sound in enclosed spaces are derived; the concept fundamental to architectural acoustics, the reverberation time (the time of decay to inaudibility), is introduced; and the principal experimental methods of investigation are given. The author’s developed theory of optimum reverberation is then presented, and the foundations are given for the acoustical design of rooms, as well as methods for correcting unsuccessful rooms. This part constitutes the center of gravity of the book and is set forth fully and systematically. The third part treats the question of sound insulation in pro—

…industrial and public buildings. Despite the large amount of data collected by the author and showing that intensive experimental work is under way on this question and that rich empirical material has been accumulated, it must be admitted that this practically most important area of architectural acoustics is still in an embryonic state. On the question of the expedient construction of buildings with respect to acoustic insulation, or of construction according to special acoustic data (scientific laboratories, hospitals, etc.), there are as yet no firmly established data suitable for use in building practice. Here is an open field for further investigations and theoretical calculations.

Considering the book as a whole, one would like to note that all research in architectural acoustics is somewhat detached from the latest data in the study of speech and hearing (physiological acoustics), where major successes have recently been achieved. Thus, for example, the author does not at all use the now generally adopted term “loudness” (Lautstärke, Loudness), as a subjective sensation, in distinction from the objective intensity of sound. The whole study and calculation of room acoustics is conducted according to data for absorption and reflection referred to the tone of 512 cycles/sec, whereas we now know that the most important region for the clear transmission of speech lies between 800 and 1000 cycles/sec. Nor is the question illuminated that the most advantageous reverberation time is a function of a person’s “two ears,” thanks to which stereophonic acoustic perception is possible; for persons deaf in one ear and in transmission by radio, the most advantageous reverberation time must be much shorter, that is, strongly damped rooms must be used.

In conclusion, one must regretfully note the large number of misprints and oversights admitted in the book, both in the text and in the drawings, and express the wish that the next edition be edited more carefully.

S. Rzhevkin.