when i'm high just from weed i always get all kinds of audial hallucinations. one time i remember specifically, i was sitting in a park after smoking a lot of weed, and i could hear what sounded like a concert in the distance. but it sounded very real, like as if it were maybe half a mile away, and the surrounding trees and houses were blocking some of the noise.
i continued to listen to the band play; the music was changing slightly from a jam band style to reggae to ska etc. i was sort of zoning in and out of hearing the music, and when i zoned back in, a different band would be playing, like it would be a totally different style and sound. i remember thinking "dammit, i want that last band to keep playing, this one sucks".
but i also hear all kinds of music in my head when im dead sober as well...
oh and when i tried shrooms everything that was happening had some kind of rhythm to it; i could hear this song in my head that continued to play throughout the majority of my trip, and when people talked it was like they were saying the lyrics to the song, everything seemed to fit the song perfectly... it was such an awesome experience to see all that happen like that.