Fog Horns

One of my favorite things about living in my first SF apartment (on Leavenworth St in Nob Hill) was listening to the fog horns while falling asleep at night.

When I moved into Eureka Valley, and later to the Mission, I was surprised that I could still hear them on occassion. I mentioned this to my sister a few weeks ago when we were down by the water. She was really surprised, and asked if I was sure that it was actually fog horns that I was hearing. I thought, "They sounds like fog horns. What else would they be?"

Well, here I am sitting in my office in my Eureka Valley home on a clear and sunny day.

...and I can hear fog horns out in the distance.

hmmm...

what else would it be?

is there such a thing as "generic boat horns"?