ASA 125th Meeting Ottawa 1993 May

2aAO8. Statistics of shipping noise vertical directionality in shallow water.

Stephen K. Mitchell

Appl. Res. Labs., Univ. of Texas at Austin, Austin, TX 78712

Even a cursory examination of ambient noise from a region of moderate or high shipping density shows that one of the most important features of noise in the frequency region from approximately 10 to 1000 Hz is its variability. A useful statistical summary of a noise time series n((theta),t), where n((theta),t) is the beam noise level from a vertical array steered in direction (theta) is the sample distribution function D[sub n](L). D[sub n](L) is computed from data as the fraction of time for which the noise n((theta),t) is less than or equal to L. A practical problem is to use known shipping densities for an area, together with a description of the acoustic propagation environment, to predict the distribution, D[sub n](L). In this paper, an approach is presented for modeling the distribution function of vertical beam noise, and to demonstrate a comparison with experimental data from a shallow-water region. [This work is supported by the Office of Naval Research, Code 23, through Block RL3B.]