On the same trip that I made the Wave Organ recordings, I woke up in the middle of the night to hear fog horns off the coast. Even in a North Beach hotel room, the sound was clear.
In the first recording, you’ll hear some vehicles on the street, and also the constant low-pitched rumble of the climate control system in the building next door:
The second recording is an odd, warbly version of the same file with a noise removal filter applied — my attempt to remove the ambient machine noise:
This serves as a cautionary example of what can happen when you get carried away trying to “fix” recordings with software. (In this case I was using Audacity’s noise removal capability — not the fault of Audacity, just a user with an itchy slider finger.) File this one under Happy Accidents.