I found something very interesting in David Paulides' 2008 book The Hoopa Project: Bigfoot Encounters in California. In the sighting I just read today, Paulides makes a very good point on something I'd never really thought about before: Bigfoot's sense of hearing.
The sighting happened to a young man who was coasting down a hill on his motorcycle late at night with the engine off, so he wouldn't annoy all the neighbors. As he was coming down the hill, he spotted a Bigfoot. It didn't even seem to notice him - until he got about 10 feet away from it!! When the creature noticed him, it stood up from the crouched position it was in and walked off. Paulides mentions other sightings (that are also in the book) where the witness has also come very close to a Bigfoot that didn't seem to hear them coming. Maybe Bigfoot has bad hearing?
That'a all I've got on this for now, I'll probably do some more research on Sasquatch's hearing later, though, so you might see another post like this one in the future.
Also, be expecting a book review of The Hoopa Project sometime in the near future.