This video, via bitmat23, demonstrates using brainwaves to control a Korg Monotron synthesizer:

This is a brainwave controlled synth i made for a mate for his birthday. The frequency of brainwaves is sent from the sensor digitally to the base station, all I have done is mod the monotron to have a cv/gate input and added a few components to the force trainer to output a voltage determined by the brain activity sensed.

Now, instead of it looking like you’re checking your email when you perform, you can look like you’re meditating!

It might be more interesting to patch this to use the CV output as a modulator, such as controlling the filter cutoff of a sequenced riff.