Volume Reverberation as a Function of Single Frequency Pulse Lengths and FM Sweep Rates

Abstract

Volume-reverberation tests were conducted with a vertically directional transducer at a frequency of 15.4 kHz. For each of two source levels, the system was capable of transmitting single frequency (SF) pulses of 10-, 50-, 100-, 300-, and 1000-msec duration and 1000-msec frequency-modulated (FM) pulses swept 100, 200, and 400 cycles. The relationship between volume reverberation level and pulse length is investigated. The data show a less than linear dependence of volume reverberation on pulse length and a linear dependence on source level. Reverberation levels for FM and SF pulses of 1000-msec duration are discussed. Although the amplitudes of the deviations from the mean reverberation are lower in the FM mode than the SF mode, no significant difference in mean levels is observed.