if your radio is still on, maybe you're talking about the alternator noise that you hear more and more you rev'up.
If not maybe you had the same trouble i allready had with my 2002 GT. Try experience this.
Is the sound only apear when you press the gas just a little?
Do you hear the sound on each gear?
try driving at about 40mph and try each gear, all at the same speed.. If your hear the sound stronger bad news dude
Tranny problem for me, Some bearing to change...