title: Wind-generated ambient noise in a topographically isolated basin: a pre-industrial era proxy.
abstract: During the mid-1980s, calibrated measurements of ambient noise and wind speed were made in the Tongue of the Ocean in the Bahamas to quantify the spectra and statistics of wind-generated noise. This deep basin is topographically isolated from the Atlantic Ocean and, therefore, largely acoustically decoupled from the Atlantic Ocean deep sound channel. The quantitative effects of contaminating (non-surface wind-generated) noise sources within the basin were eliminated by careful measurement and robust statistical analysis methodologies. Above 500 Hz, the spectral slopes are approximately -5 dB per octave and independent of wind speed. Below 500 Hz, the ambient noise is no longer a linear function of wind speed. Below 100 Hz and for wind speeds greater than 18.5 knots (kt), the ambient noise is independent of frequency. The minimum observed ambient noise level falls 13 dB below Urick's "light shipping" level at 30 Hz and 2-5 dB below Wenz's sea state zero level through the wind-dominated portion of the spectrum. The basin's geographical isolation and the rigorous measurement and analysis methodologies employed make this two-decade-old data set a reasonable and justified proxy for pre-industrial era ocean noise levels in the 20 Hz to 20 kHz frequency band.
authors.affiliation: Department of Oceanography, Naval Postgraduate School, 833 Dyer Road, Monterey, California 93943, USA. dbreeder@nps.edu
authors.forename: D Benjamin
authors.initials: DB
authors.lastname: Reeder
authors.forename: Edmond S
authors.initials: ES
authors.lastname: Sheffield
authors.forename: Susan M
authors.initials: SM
authors.lastname: Mach
mesh_terms: D000162:Acoustics; D001444:Bahamas; D005844:Geology / Q000379:methods*; D015233:Models, Statistical; D009622:Noise; D009792:Oceans and Seas; D011312:Pressure; D012623:Seawater; D013018:Sound Spectrography; D014919:Wind