I have been using MAX/MSP to control LED stage lights through DMX- using my computer as an interface to control lights with the sound of my flute playing. I wanted to close the circle (process my flute playing) with the lights, and for that, I used light sensors. With that system, I can make feedback loops between light and sound. I have made a few pieces with this already, and I have not exhausted the possibilities yet.
This is a proof of concept Feedback between sound and light: change in sound triggers changes in light, changes in light triggers changes in sound.
On the video I am using photoresistors to modify the sound. I haven them connected to the computer through an ESP32. The response of the sensor changes with the brightness of the light. At the same time, the lights are connected to the computer as well, so they respond to the sound.
I am using the microphone to create feedback with the transducer on the table, thus having two feedback loops at place (light/sound and mic/transducer).
On this second video I followed the same light/sound feedback principle, but in this case I used an RGB sensor instead of the photoresistor. The difference here is that I can get values for the brightness of red, green, and blue.
In this instance, I used simple sine waves to check the response of the sensor but then I used this system to code a patch that applies live electronic processes to my flute playing.