That wouldn't be possible without getting rid of most of the in-game speech, unless an MSU-1 patch was developed. Even if they had it, the music in the Genesis version of NBA Jam and the SNES NBA Hangtime was extremely simplistic. The former game's in-game music had two channels and no percussion.
Thanks a lot for the info, I didn't know that. I was just curious, as I always thought the game felt more alive with in-game music even if it was very simplistic. But in this case, I think it's preferable to have varied in-game speech and listen to the music of your choice outside the game while playing if you'd like to.