There is no question that this monograph provides much excellent critical analysis of data dealing with many facets of the effects of noise, and can therefore serve as an introduction and bibliographic source reference for any contemplated more thorough study of such facets. However, the coverage is far from complete: Besides the exclusion of literature in foreign languages, and of most animal studies, topics mentioned only briefly, if at all, include auditory effects other than loss of pure-tone sensitivity (e.g., changes in differential thresholds, tinnitus, etc.), the physiological substrate of even pure-tone loss, individual differences in susceptibility to damage, and the whole field of hearing protectors. In addition, the level of critical insight is not uniform, nor is the accuracy of the presentation: All too often experimental parameters are misstated, graphs and equations are reproduced without enough accompanying information to permit them to be understood, or experiments are misinterpreted. Indeed, some studies are ignored whose results challenge the validity of assumptions that Kryter makes in order to support his idiosyncratic recommendations for noise regulations. So although this book will be an indispensible asset to any future investigator concerned with one of the effects of noise on man, it is only a starting point, not a final authority: It will still be necessary to study original sources in order to achieve a balanced view of the state of knowledge about the noise effect under consideration.

No abstract

Slock 20. Abstract (cont'd) than those obtained when the maximum was directed seaward. This difference or anisotropy (seaward vs. shoreward), which depends on range from the beach, on frequency and on surf intensity, was 10 dB at 300 Hz at the 9 km site during very heavy surf. Surf beat was clearly audible when the cardioid maximum was steered shoreward at ranges as great as 2 km. During heavy surf, the omnidirectional ambient noise levels also increased significantly in the same frequency range at which the anisotropy is evident. The anisotropy effects diminish both in magnitude and in frequency range with lower wave hexght but are still observable during light surf. We have concluded that intense breaking surf can contribute significantly to ambient noise in fairly deep continental shelf waters.

The elastic coefficients of benzene are determined from sound velocities measured with the use of an ultrasonic pulse technique over a temperature range of 170° to 250 0 K. At 250 0 K the results are (in units of 10 10 dyn/cn;2): cu=? 14; C22=6.56; .c33=5.83; c«=1.97; C55=3.78; C66=1.53; cI2=3.52; cI3=4.01; C23=3.90. The~e elastic coe~Clents generally mcrease as the temperature is lowered. The observed absorption coeffiCIents are relatively large, thus confirming data reported by L. N. Liebermann. However. it was found that .the .absorption is not isotropic a~d that the absorption for shear waves is comparable with that for longltudmal waves. Some of the expenmental techniques used are described.

The acoustic impedance of a Helmholtz resonator terminating a ten-inch diameter tube has been investigated for sound pressure levels in the resonator of from 100 db to 170 db and for a range of particle velocities in the neck of from 1.3 cm/sec to 1.2×104 cm/sec (rms). Two different mounting orientations showed the same general rise in acoustic resistance and rise in resonant frequency with increasing sound pressure level but gave quite different results in detail.