With Mars' thin atmosphere, how would sounds like the wind be interpreted
by
a human visitor? Would things sound "unearthly"?


That's an interesting question. You could actually simulate the conditions
if you had a large vacuum chamber evacuated to Mars surface pressure. Then
you could introduce wind with a fan and have sand of the same consistency as
the Martian surface. Record the resulting sounds and that would probably be
your closest approximation.

Ash