Measurement of the Attenuation of Low-Frequency Underwater Sound

Abstract

Underwater sound signals from the deep atomic explosion of Operation Wigwam in May, 1955, were recorded on bottom-mounted hydrophones at Point Sur and Point Arena, California, and Kaneohe Bay, Oahu. Reflected signals were recorded for two hours at Kaneohe and nearly four hours at Point Sur, and many reflectors were tentatively identified. Values for the attenuation of 20–200 cps sound in the sea were obtained from an analysis of the change in spectra of the reflected signals with travel distance. These values, plus earlier work at higher frequencies, indicate that the attenuation in db per kiloyard (kyd) over the frequency range 20 cps to 60 kc is equal to 0.033f32, f being in kc per sec.