I touch on the nature of sound on Mars in the first book, but this is new and a little wild. It’s not just the low pressure of the atmosphere that affects the transfer of sound. The composition of that atmosphere does as well. And it’s not the same across the range of sounds we hear.
From the article:
“Due to the unique properties of the carbon dioxide molecules at low pressure, Mars is the only terrestrial-planet atmosphere in the Solar System experiencing a change in speed of sound right in the middle of the audible bandwidth (20 Hertz to 20,000 Hertz)… The result of this is that sound travels more than 10 meters per second faster at higher frequencies than it does at low ones.”
ScienceAlert