Abstract: Environmental acoustical analysis of cw, SUS, and ambient noise are reported for the Parece Vela Basin and the Western Philippine Sea Basin. These data were collected during the exercise CHURCH STROKE II Cruise 5, held in the Philippine Sea during the fall of 1977. Raw acoustic data were recorded on remote bottom moored ACODAC and PAR systems. During the recording periods ambient noise, ship signatures, and storm noise were recorded as well as cw and SUS data. Bottom loss and propagation loss are reported for the different basins. The Parece Vela Basin is characterized as bottom limited and high bottom loss for grazing angles greater than 40 deg. The Western Philippine Sea Basin is characterized as an area of depth excess and high bottom loss.

Understanding the effectiveness of sonar systems is essential for assessing their operation in pro- or anti- submarine warfare. Sonar performance varies from one ocean environment to another, with large variations in detection range resulting from differences in acoustic propagation conditions. In most instances the factor which has the largest effect on long-range propagation is the sea floor. This factor also has the largest variability from one location to another. Understanding and prediction of the interaction of acoustic energy with the sea floor is complicated by the penetration of the energy into the sediments and rocks that make up the sea floor.......