Is there a way to up the pitch on the phone receiver for the Treo 600? Sometimes it sounds like the speaker has too much bass in it. Is there anyway to add some treble?

Don't have the problem with pTunes because I can use the equalizer. But some people that I talk to have deep voices and it would be nice to add some treble to the big built-in ear speaker. When I shift to handsfree speaker it is fine or when using earbud I can put my finger on the bud shell and raise the pitch.