Vertical directionality of ambient noise at 32 degrees N as a function of longitude and wind speed

Measurements of the ambient-noise field between 50 and 300 Hz with vertical arrays at 32 degrees N (124 degrees W, 136 degrees W, and 150 degrees W) have been made. Substantial differences in the vertical distribution of noise have been measured (especially at the higher frequencies), which can be interpreted in the context of attenuation by seawater sound absorption of coastal shipping noise. Under low wind-speed conditions, the vertical distribution of ambient noise is clearly concentrated within approximately +or-15 degrees of the horizontal. High wind speed has the effect of filling in the higher vertical angles, while leaving the level within the low-angular region unchanged.<
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