Beginner 6 minutes
Sound underwater: you hear everything and can't tell where it's coming from
Why sound travels faster and farther, and why your ears stop being able to locate it
Underwater you can hear a boat engine with total clarity, and you're unable to tell if it's coming from the left, the right, or above. It's not a problem with you: it's a physical limitation of how your ears work in a medium where sound travels four times faster.
In this article you'll see why sound travels better in water than in air, why the human ear loses its ability to localize direction, and what implications all this has for communication and safety.
It affects how you communicate underwater, how you detect the presence of boats, and it explains why diving communication is essentially visual rather than sound-based.
Faster and farther
Sound is a pressure wave that needs a material medium to propagate, and it travels faster the less compressible (the stiffer) that medium is. Water is far less compressible than air, which is why sound moves through it at a much higher speed.
The result is that sound travels through water at about 1,500 meters per second, compared to roughly 340 in air: around four times faster. And not just faster: it also attenuates less with distance, especially at low frequencies.
That's why low-frequency sounds can travel enormous distances underwater, and why marine mammals bet on sound as their main channel, as you saw in the article dedicated to them.
For a diver, the immediate consequence is that you hear far more than you'd expect: engines, anchor chains, the noise of other divers, the constant crackle of the reef itself, which on a healthy reef is surprisingly loud, mostly from shrimp and fish.
Keep reading with full access
This article is part of the full Encyclopedia. A donation from USD 10 unlocks every article, every species photo and the downloadable app, and helps sustain the Scuba Sign Paperless Diving Community project.