cut twice, measure once

foghorn frequencies

DSCF0038 Low Tide at Doran Beach, Near Bodega Bay1

My partner and I had a great MLK Day weekend where we got to take a little trip to the California coastline - specifically, we enjoyed some time at Bodega Bay.

Fun fact, I grew up in Hawaii where the average temperature is about 80F - the water is warm and pretty humid. Moving to California has been very different as it is usually dry and cold. Notably, the beaches and the water is freezing. Also, there's fog.

Fog is such an interesting phenomenon for me. With fog comes fog horns. As you venture up and down the beach in Bodega Bay, you'll hear the rhythmic toots of a fog horn - less horn, more like a digital generated tone; but a fog horn, nonetheless.

My partner is a musician so it always piques my curiosity when there is a repeated tone out in the wild and I will ask her, "What note do you think that is?" She guessed somewhere between G and A and we pulled out a piano app and tested it by ear. G#4!

note_spectrogram A Spectrogram of Foghorn Frequencies

Well I had to check it out for myself and it turns out, it's 415.305 Hz or G#4 (or Ab4, if you're into that kind of stuff). Being the nerd that I am, I took an audio recording from a Youtube video titled, "Bodega Bay Sunset fog horn" and put it in Python and created a spectrogram of the sounds found in the video. Lo-and-behold, G#4 is showing a repeated pattern every ten seconds.

Neat2!


  1. Shot with X100VI by me.

  2. Various frequencies and tones of fog horns

#photography #python