If you mean mp3's, there's no player/driver that I'm aware of, but I'm sure the processing time it would take to decompress an mp3 wouldn't make it worth while at all. Even then, a 1 minute song is about 1mb so you're still eating up a lot of rom space. Your best option is to use something like shiru's tfm tracker and driver, or similar, that uses FM music. If you want to use PCM data for long music samples instead of a quick 3 second sound effect, you're on the wrong generation of consoles (unless you're going with the sega cd)
And for the record, a 16000hz, 8 bit, mono 4 second wav file runs at about 35kb, possibly closer to 60kb (can check when I get home). Multiply that by 15 and that's the approximate size of a 1 minute song (between 525kb and 900kb, think of how much code can fit in that space, plus you'd only have enough room for 4 songs, if the driver isn't too big that is).