Here is the black box that sends music to the transducer. I guess it's like a radio or amplifier, in the case of record players (something people had in the old days). It only plays one song, which sounds like faint random clicking.
That strikes me as fairly limiting. I don't know what kind of music the mussels here like or don't like. It could be different from mussels in other parts of the world. Also, mussels and barnacles might like different kinds of music. I don't know.
It would be better to have different choices to test. Do mussels like ACDC better than Beethoven? That might be useful to know.