JVC DVD player plays with distorted sound

My DVD player has started to distort the sound. I've tried several discs both old and brand new. It's not a disc problem. It muffles the sound and acts almost as if it's on a slower speed. The picture is fine, just the sound is distorted. The odd thing is that it was sudden. One night it was doing just fine and the next, using the same DVD that was left in the player, it started to distort the sound.