Back in the late 1970s, my sister and I agreed on little. Her taste in music was especially problematic for me. However, when she moved out of the house, she left me a strange device that was popular at the time — a set of colored lights behind frosted glass and set in a wooden box, through which you would pass through your speaker wires so the lights would seem to dance with the music being played.
Turns out, we could have just used a squid.
The video below is quite amazing. How does it work? The scientists tell you:
An iPod plays music by converting digital music to a small current that it sends to tiny magnets in the earbuds. The magnets are connected to cones that vibrate and produce sound. Since this is the same electrical current that neurons use to communicate, we cut off the ear buds and instead placed the wire into the fin nerve. When the iPod sends bass frequencies (<100Hz) the axons in the nerves have enough charge to fire an action potential. This will in turn cause the muscles in the chromatophores to contract.