Reflection of Sound from Coastal Sea Bottoms.

An experimental method has been developed for measuring the reflection coefficient of the ocean bottom for supersonic sound at grazing incidence. In this method the geometry is controlled so that the resultant of the direct and reflected rays passes through consecutive maxima and minima at the hydrophone. The amplitude reflection coefficient is given by the expression (M - m)/(M + m), where M is the amplitude of a maximum and m is the amplitude of the following minimum. Using this method, with a grazing angle of nine degrees, the following values were obtained for the reflection coefficients at 17 stations near Woods Hole: mud-0 to 0.20, mud-sand-0.20 to 0.40, sand-mud-0.40 to 0.60, sand-0.40 to 0.85, stony-0.50 to 0.85. It is observed that the reflection coefficient depends not only on the median size of the particles making up the bottom, but also on the sorting of the particles and on the bottom topography. [ABSTRACT FROM AUTHOR]