I've never got color-sound synesthesia Though I've seen ideas, felt mood through taste buds and things like that...
Had to comment, because I was at sea of dreams this year despite my location! I once thought I was hearing voices, and a girl screaming while i was on mushrooms. Once that happens I think certain people ignore it and certain people become more alert (which I think leads to more intense auditory hallucinations - listening for them). It turned out that my neighbours were having a fire and they were drunk and laughing etc. and I heard it through my window. Auditory hallucinations honestly make me nervous while on psychedelics. At least when I am tripping hard enough to hear weird waves and stuff but not tripping hard enough to have an ego death and experience being the waves. Voices aren't common for me. If I legitimately was hearing voices I probably would have discontinued the use of psychedelics. Giving the brain a bit of sound to focus on like music or a podcast usually helps me if I'm hearing weird sounds, because as of yet I have not found any benefit to just sitting there and listening to the weird sounds, it just makes me feel like im psychotic.
The voices I would hear were actually comforting but I understand where you're coming from. I used to eat shrooms every week and when you're using that often, it can reach a point where you keep getting the same trip. Once on a rather large dose of shrooms I was laid out on the floor in deep contemplation. At this point some friends were knocking on my door and calling my name, I thought I had imagined it until they later told me they actually did stop by To me it seemed amazing, because while a trip takes place sometimes it seems like your mind is manifesting things around you and it is in a way.
I remember one time I was tripping in my living room and a police car with his sirens blaring drove by...... The rest of the night I could swear I could hear cops running up my porch and shouting commands...... Could hear dozens of police cars pulling up outside. I just hid under my bed until morning.
I used to hear music each time. A couple of months ago i saw two pale figures and a bright light ehich were accompanied by music and a blaring, trumpetting sound. Ever since that time ive been hearing music everywhere, sober. Not a perma trip, just accustomed to eat since i take a trip weekly, if not more than once.