Reflection of Underwater Sound from the Sea Surface Available to Purchase

Information on the instantaneous sea surface reflectivity for 30‐kc sound has been obtained. The method required that the submerged source and receiver be rigidly mounted on towers resting on the sea bottom. Transmission of a frequency‐modulated sound pulse results in an interference pattern at the receiver; interference occurs between the direct and reflected sound. Analysis of these interference patterns reveals the following: The average time of persistence of the pattern is five‐hundredths of a second. Under the conditions of the experiment, surface reflectivity is highly frequency dependent. The median value for the reflection coefficient is near to unity. Approximately 10 percent of the time the sea surface focuses the sound, giving a a reflection coefficient greater than unity.