Check out the Wave Organ if tide’s right:
https://www.exploratorium.edu/visit/wave-organ
The sizable Presidio and Golden Gate Park are almost dense enough in parts to get lost in, though much of the nature in the city isn’t remote enough to get away from car sounds.
There are some nice quieter beaches, in the bay not along the ocean, like Baker Beach and China Beach.
Definitely head up to Muir Woods if you can (north of the city).
Music wise, check out calendar at http://bayimproviser.com/calendar.aspx — especially the Thursday-evening shows at the Luggage Store Gallery Music Series in San Francisco.
Record-store wise, in San Francisco proper: Amoeba, Stranded. There’s a bunch. Folks may have other recommendations.