Biospheric - Underwater Noise

Underwater Noise

Biospheric Engineering Ltd. provide underwater noise monitoring and prediction capability. Our equipment is capable of measuring noise in the frequency range of 1 Hz to 600,000 Hz. Measurements are made with calibrated hydrophones, traceable to international standards, so that accurate impact predictions can be made.

In shallow waters (less than 100m) noise propagation is a complex issue. Reflections from the surface and the bottom as well as underwater contour faces has a major impact on how noise will propagate at any site. Using hydrophone arrays and calibrated techniques we can establish site specific noise propagation characteristics, thus enabling accurate impact predictions to be made.

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Humpback Whale Tail Slapping

General information on underwater noise levels

Underwater decibel levels are generally much higher than decibel levels in air (see why here). Some examples of underwater noise levels are given below.

Natural and human-made source noise comparisons.
Nosie Source	Maxiumum Source Level	Remarks	Reference
Seismic Exploration Devices	212-230 dB	Includes vibroseis, sparker, gas sleeve, exploder, water gun and boomer seismic profiling methods.	Johnston and Cain, 1981; Holiday et al., 1984.
Container Ship	198 dB	Length 274 meters; Speed 23 knots	Buck and Chalfant, 1972; Ross, 1976; Brown, 1982b; Thiele and Ødegaard, 1983.
Supertanker	190 dB	Length 340 meters; Speed 20 knots	Buck and Chalfant, 1972; Ross, 1976; Brown, 1982b; Thiele and Ødegaard, 1983.
Blue Whale	190 dB (avg. 145-172)	Vocalizations: Low frequency moans	Cummings and Thompson, 1971a; Edds, 1982.
Fin Whale	188 dB (avg. 155-186)	Vocalizations: Pulses, moans	Watkins, 1981b; Cummings et al., 1986; Edds, 1988.
Offshore Drill Rig	185 dB	Motor Vessel KULLUK; oil/gas exploration	Greene, 1987b.
Offshore Dredge	185 dB	Motor Vessel AQUARIUS	Greene, 1987b.
Humpback Whale	180 dB (avg. 175-180)	Fluke and flipper slaps	Thompson et al., 1986.
Open Ocean Ambient Noise	74-100 dB (71-97 dB in deep sound channel)	Estimate for sea state 3-5; expected to be higher (= or > 120 dB) when vessels present.	Urick, 1983, 1986.

Note: Except where noted, all the above are nominal total broadband power levels in 20-1000 Hz band. These are the levels that would be measured by a single hydrophone (reference 1 µPa @ 1 m) in the water.

Biospheric Engineering Ltd., Truskey East, Bearna, Co. Galway, Ireland.
Tel: +353 (0)91 591336
Send mail to info@biospheric.ie with questions or comments.
Copyright © 2010 Biospheric Engineering Ltd.

Underwater Noise

General information on underwater noise levels

Natural and human-made source noise comparisons.

Note: Except where noted, all the above are nominal total broadband power levels in 20-1000 Hz band. These are the levels that would be measured by a single hydrophone (reference 1 µPa @ 1 m) in the water.