(youtube) A project for Music Hack Day MIT 2012.
I got a running watch last Christmas that included a heart rate monitor. I noticed that the range of human heart rates and the range of music tempos are pretty similar, so I thought it would be funny to control the tempo of a song with your heart.
The heart rate monitor communicates wirelessly with the watch. I don't know how to hack the radio signal that the heart rate monitor sends out, so I decided to approach reading the heart rate in a much more roundabout way. I duct taped a webcam to my running watch, and wrote a program in Max/MSP to do some really hacky OCR to determine the digits. I then take this heart rate, divide it by the original tempo of the song, and use that number to control the rate of song playback. Enjoy!