sound levels

Sound levels in air

Please see noise.

Sound levels in water

Measurements (in decibels) of sound levels in water are not equivalent to those in air. In air, a level of 120 decibels is painful for humans. In water, it takes 195 decibels to make divers equally uncomfortable.

Approximate level in dB	Source	Air equivalent
220	Air guns used in geophysical surveys
209	Heard Island experiment (1991)	270 dB
up to 220	dolphins
180	fin whales
180	freighters
	underwater volcanic eruptions & earthquakes
150	polar ice pack
	boat with outboard motor
130	breaking waves, 30-knot wind

According to John R. Potter, Marine Physical Laboratory, Scripps Institute of Oceanography, as reported in:
Malcolm B. Browne.
Human noises in ocean held to threaten marine mammals.
New York Times, page B5, October 19, 1993.