Distance from Source to Reach 180/170 dB Intensity Level

AI Thread Summary
The discussion revolves around calculating the distance from a sound source in seawater where the intensity level drops to 180/170 dB from an initial measurement of 237 dB at 1 meter. The equation used is SPL = 237 - 25.35 log(R), but the calculated distances appear inconsistent, suggesting a value much lower than expected. Participants highlight that factors like wavelength absorption, sea floor depth, and reflections can significantly affect sound intensity and distance calculations. The logarithmic nature of the scale means that even small changes in distance can lead to large differences in intensity levels. Understanding these variables is crucial for assessing the impact of sound on marine mammals.
JoaoCorvina
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Not a homework... simple curiosity by trying to know this a bit better in order to learn and understand possible effects of sound to marine mammals auditory systems.
In sea water, at distance of 1m from a localized sound source, you measure the intensity level as 237 dB.
How far away from the source must you be for the intensity level to fall to 180/170 dB? I am trying to do this but i come up with distances that don't seem right to me...

Been using this equation taken from http://www.underwaternoise.org.uk/measuring_noise/source_level.shtml

SPL = 237 - 25.35 log(R)

by replacing SPL with 180 dB, R comes up with a ow value for the distance which shouldn't be that low... it should be around 500m, distance that we consider to be safe for marine mammals.

Am I doing it right?

Would appreciate some help and some explanations!
 
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~180m is not so far away from 500m, especially with a logarithmic scale. With 170dB, it is very close to 500m, and some safety factor is always a good idea.

In addition, several factors can change the formula:
- different wavelengths can have different absorption in water
- if the depth of the sea is not large compared to the horizontal distance, the floor can be relevant.
- reflections elsewhere can be relevant
- ...
 

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