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.

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