Does higher air pressure result in louder sound?

07 August 2011


Dear Chris,

I have a question I'd like to hear your opinion on.

Loudness of a sound decreases when air pressure decreases. No sound can travel in a vacuum.  However, does this mean that higher air pressure would result in louder noises? Do deep-sea divers in decompression chambers have to keep their voice down because sounds appear louder?

Love the show! As a science teacher in training, I am learning a lot of things relevant for the classroom that I would never get from academic training. 

Kind regards, Malte from Hamburg, Germany


Dave - I don't know about deep sea divers, but the effect related to how efficiently you can couple vibrations - so get a vibration from the musical instrument, or your voice, into the air, then from the air into your ears. With all of these transitions, you tend to get some sound carrying on and some sound reflecting. And the more similar the material which you're going from and to, the more energy it gets transferred, so if you're going from one bit of air to another bit of air, pretty much all of the energy is transferred from one to the other. If you're going from air to a solid piece of steel, almost none of the energy is transferred and actually, vice versa; If you're going from a solid bit of steel almost none of the energy is transferred into the air and all of it is reflected. So if you have very, very high pressure, it increases the pressure of air, it's going to increase its density and make it seem to the sound wave more like the musical instrument or more like your ear so more energy will get transferred, everything will get more efficient, and I would've thought you would hear things louder.

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