Re: How would sound propagate through Mars' atmosphere?

Hi Chris,

Thanks for your interesting question. As an Acoustical Oceanographer, I spend a lot of time thinking about differences in sound propagation between the water and the air, but I’d never thought about the atmospheres of other planets before. Luckily, other researchers have. I found a nice paper which you can see here or here.

On Mars, sound travels slower, about 2/3 the speed of sound in Earth’s (so the trick of counting the seconds between lightning strike and thunder clap would be different there, not that you’re likely to get to try it) and is attenuated much more quickly. Attenuation is a measure of the amount the sound-pressure waves decrease in amplitude as a function of range. It depends mainly on temperature (somewhat colder on Mars) and the chemical composition of the atmosphere (mostly carbon dioxide on Mars and nitrogen on Earth) and only to a lesser extent on the density, or thinness, of the atmosphere. Venus’s atmosphere, which is much thicker than Earth’s but is also primarily composed of carbon dioxide, has higher attenuation than Earth’s over much of the audible frequency range (see Fig. 1 in the paper mentioned above).

It is this attenuation, which at any given frequency is about 100 times larger on Mars, which would make the sound from your stereo quieter – though how much you noticed it would depend on how far you were from the stereo. Certainly, sounds that can be heard many kilometers away on Earth, you’d be hard pressed to hear at the end of the block on Mars.

I hope this answers your question. Feel free to contact me if you have any further questions.

Cheers,
Tetjana