The microphone will be sensitive to the same frequencies as the human ear : between 20 Hz and 20 kHz. A first problem occurs with that : the Martian atmosphere is very thin and those frequencies do not travel for long distances. Nevertheless, the wind on Mars can be strong enough to generate noise and the rover too. So, here is a list of possible noise sources that could be heard by the microphone :

• Dust storms and dust devils : those can be dangerous for the rover. Only small size dust devil might be audible. Bigger ones make sound in lower frequencies.
• Saltation : Martian particles of dust which are in the air will hit the rover. This might produce a
  noise which can be heard by the microphone. Data may give the information of how many
  particles hit the rover, which can help to know better the Martian environment for future
  missions.
• Wind over the rover : as the wind blows over the MSL2, it might produce sounds. In addition, we should also hear sounds made by the laser SuperCam.

Dust devils seen by SPIRIT

July 13, 2005
Credits : NASA/JPL/Texas A&M