Have a look at the RBOOM record from a quiescent period below. The instrument is in our beach cottage, with everything electrical turned off except for the Boom and an RS alongside it. There are houses 50 m away, but they’re unoccupied at present. It’s a very quiet place.
In the spectogram, you can see a background hum at 12.4 Hz.
But when an event occurs (a wind gust perhaps), the hum increases in energy.
In my field (tsunami propagation) , we would call this “seiche” or resonance: an embayment or harbour oscillates quietly at its natural frequency, but when a wave or waves come in that contain a range of frequencies, the natural frequency gets amplified many-fold preferentially. It’s a primary cause of inundation from tsunami.
Can someone interpret the hum in the Boom signal for me?
Is it something in the instrument itself?
Or is it a natural phenomenon? If so what can it be?