sound problem with 'need for speed III' psx

[dark heart]

hi, i managed to get my copy of need for speed 3 onto my psp using psx2psp, and it worked fine.
but when i played the game there was no music.
it does try to play the music, but can only cough a split second of sound at the start of the race, and in the menu.
is there anyway to get the music to work? it kinda keeps you concentrated on the movements of the game. thanks in advance