I just went down a similar no Gorgar sound issue, or issues. Mine quit talking, then no sound, then sound but not talking when I replaced all the sound roms. I finally dropped $110 on a new board and the problem is fixed.
Have you reset the sound roms? If you attempt this, be careful not to bend or break pins on removal.
If you think it might be the speaker and you are on the factory speaker replacing it wouldn't be a bad idea.