There have been experiments done (including with humans) that indicate several
things.  Congenitally blind folks actually do have better hearing probably
because they are using parts of the visual cortex to help process sound.
Second, blind foldes subjects seem to "listen better" but until recently there
was no good evidence of a true hearing difference.  Third, new evidence is
beginning to come in that prolonged blindfolding may improve hearing.  There is
still a question as to whether this is permanent (it seems not to be) and how
much improvement there really is.

All told, its a really interesting area.

As an aside, those blinded in later life do show some demonstrable hearing
improvement but not as much as the congenitally blind.

Tom


Tom Brennan  KD5VIJ, CCC-A/SLP
web page http://titan.sfasu.edu/~g_brennantg/sonicpage.html