Statistical Analysis of Sound Transmission Results Obtained on the New Jersey Continental Slope

The ACT II (Acoustic Characterization Test II) experiment was conducted near the site of AMCOR Borehole 6010 on the New Jersey shelf. It is one of a series of experiments, a major objective being the evaluation of propagation predictability in sandy shallow water environments. The influence on nonlinear frequency dependence of the sediment volume attenuation in the uppermost sediment layer is considered here. A metric for its effect on the degradation of transmission loss with range is an effective attenuation coefficient. A previous study [W. M. Carey, and R. Evans, IEEE J. Oceanic Eng., vol 23, pp. 429-447, 1998] determined that a frequency power exponent of 1.5, relative to a reference frequency of 50 Hz over the frequency interval 50-1000 Hz, provided the best comparison with the data. Our approach uses 1 kHz as a reference frequency and extensive comparisons between measurements and PE calculations. This procedure leads to a higher frequency power exponent with the assumption that the surface layer attenuation at 1 kHz is approximately 0.35 dB/m [J. X. Zhou, and X. Z. Zhang, IEEE J. Oceanic Eng., vol 29, pp. 988-999, 2004]. The statistics of intensity fluctuations are also examined for both measurements and calculations. Experimental histograms are compared with the expected exponential distribution, and very good agreement is obtained