Sounds fine to me.
What emulator are you using ?
ZSNES has some sound issues with some games.
I use Snes9x 1.51 with envelope height reading enabled, that fixes a lot of sound related problems.
Take Contra III and Super Castlevania IV for instance, load them in ZSNES first and you'll notice that the sound FX are not sounding 100% accurate.
Load them in Snes9x with height reading enabled and they're spot on.
Of course you could also use BSNES which is the most accurate SNES emu available.