Observations of ocean ambient noise (10 Hz to 10 kHz) at the site of a former navy listening station to the west of Point Sur, California, from January to July of 2007

摘要

Ocean acoustic recordings were obtained from January through June of 2007 at the site of a former Unites States Navy listening station to the west of Point Sur, California. These data were analyzed to determine the characteristics of the ambient acoustic noise. Direct comparisons to previous studies conducted at the same location revealed a near identical match of the pressure spectrum level in the 50 to 120 Hz frequency band to a 1994-2001 study. Comparison to a 1963-1965 study revealed a 3 to 5 dB increase in ambient noise over the 60 to 300 Hz frequency band. As expected, relating ambient noise to wind speed revealed a significant (correlation coefficient greater than 0.5) correlation between 400 Hz and 10 kHz with a maximum correlation coefficient of 0.78 near 2 kHz. Comparing shipping data from San Francisco and Los Angeles-Long Beach ports to ambient noise in the 10 to 1000 Hz band revealed obvious patterns in the relationship of the number of ships arriving or departing each day and noise level. Due to its proximity, the San Francisco shipping data had a greater effect on the ambient noise level at Point Sur. The largest value of the correlation coefficient between ambient noise and shipping traffic was 0.55 and occurred at 700 Hz.