3 ms·

Could you be hearing one of the many foghorns in the bay? https://youtu.be/jJWd5eHeFY4 https://youtu.be/jJWd5eHeFY4

by mareko 6y ago

johnfn 6y ago
Pretty interesting hypothesis! I don't think so, though. It was a fairly electronic sounding boop, almost like a low sine wave. A fog horn sound has more acoustic qualities to it. Also, if it was a fog horn, I don't know why it would only be audible in Nob Hill and no where else I've been in SF.
- closeparen 6y ago
  The Bay foghorns are electronic tones; they don’t sound like classic/cartoon foghorns at all.
  - stn8188 6y ago
    If it's anything like the most common fog horn that the USCG uses across the country, it's a 273Hz tone (though I don't recall the waveform, most likely sinusoidal). As of 8 years ago, they were using the FA-232 model fog horn, the circuitry was designed in the '70s and uses discrete BJTs on the boards to generate the tone and drive the "speaker".
  - johnfn 6y ago
    Wow. I went online and found an audio recording: https://www.youtube.com/watch?time_continue=12&v=CPUs2KnAyhU&feature=emb_title https://www.youtube.com/watch?time_continue=12&v=CPUs2KnAyhU... Yup, the tone at 0:08 is pretty much the exact tone I heard. Mind-blowing. Never would have imagined that's what a fog horn sounded like. I expected them to all be much deeper tones like the ones that come a few seconds later. I guess there must be weird acoustic qualities that make only the higher toned ones carry into Nob Hill.
wpietri 6y ago
In the Mission I could occasionally hear foghorns, which made no sense to me. It was generally around first light in the morning. After quite a lot of digging, including making heatmaps of where ships parked, I traced it to Anchorage No 9, which is basically a parking lot for giant ships. You can see it when crossing the Bay Bridge. More details and maps here: https://www.facebook.com/williamp/posts/10106726609193073 https://www.facebook.com/williamp/posts/10106726609193073

Could you be hearing one of the many foghorns in the bay? https://youtu.be/jJWd5eHeFY4 https://youtu.be/jJWd5eHeFY4

by mareko 6y ago

Could you be hearing one of the many foghorns in the bay? https://youtu.be/jJWd5eHeFY4 https://youtu.be/jJWd5eHeFY4

Pretty interesting hypothesis! I don't think so, though. It was a fairly electronic sounding boop, almost like a low sine wave. A fog horn sound has more acoustic qualities to it. Also, if it was a fog horn, I don't know why it would only be audible in Nob Hill and no where else I've been in SF.

closeparen 6y ago
The Bay foghorns are electronic tones; they don’t sound like classic/cartoon foghorns at all.
- stn8188 6y ago
  If it's anything like the most common fog horn that the USCG uses across the country, it's a 273Hz tone (though I don't recall the waveform, most likely sinusoidal). As of 8 years ago, they were using the FA-232 model fog horn, the circuitry was designed in the '70s and uses discrete BJTs on the boards to generate the tone and drive the "speaker".
- johnfn 6y ago
  Wow. I went online and found an audio recording: https://www.youtube.com/watch?time_continue=12&v=CPUs2KnAyhU&feature=emb_title https://www.youtube.com/watch?time_continue=12&v=CPUs2KnAyhU... Yup, the tone at 0:08 is pretty much the exact tone I heard. Mind-blowing. Never would have imagined that's what a fog horn sounded like. I expected them to all be much deeper tones like the ones that come a few seconds later. I guess there must be weird acoustic qualities that make only the higher toned ones carry into Nob Hill.

wpietri 6y ago

In the Mission I could occasionally hear foghorns, which made no sense to me. It was generally around first light in the morning. After quite a lot of digging, including making heatmaps of where ships parked, I traced it to Anchorage No 9, which is basically a parking lot for giant ships. You can see it when crossing the Bay Bridge. More details and maps here: https://www.facebook.com/williamp/posts/10106726609193073 https://www.facebook.com/williamp/posts/10106726609193073