The speed of sound on the planet Mars depends on the frequency of its waves.
Sound is waves that travel through a medium, i.e. gases, liquids and solids. Its speed in the medium in which it travels depends on the density and composition of that medium.
On Earth the atmosphere is mostly nitrogen and oxygen while on Mars it is more carbon dioxide. Still, the air density on Earth is 160 times greater than that of Mars. As a consequence the sound there is slower. On Mars the speed is 250 meters per second and on Earth 340.
The reason the sound has two speeds there is because the carbon dioxide molecules react differently when the frequency is less than 240 Hertz and differently when the frequency is higher than that.
[Source: http://www.sciencenews.org]
