i have a friend who actually did this for a few days on a lark. he went around with a handheld tape recorder tied to his belt and pressed play as he walked into the room. various things would emerge... most notable was the porn-style wah-wah guitar riff...

when i enter any room i'm usually in the process of singing sumthin... a musical soundtrack would just confuse the issue. but my exit music is the middle part of chopin's fantasie impromptu.