How good is your heartbeat's sense of rhythm?
Ryan Challinor, an MIT student, now has an answer to this interesting question. For his school's Music Hack Day, Challinor hooked his heartbeat up to Carly Rae Jepson's maddeningly catchy hit "Call Me Maybe." When Challinor did jumping jacks, the song sped up, and poor Carly Rae sounded like a chipmunk. When the song slowed down, she sounded like a man. It's pretty awesome.
For the tech geeks out there wondering how this works, Challinor apparently "took his heart rate, divided it by the original tempo of the song and used that number to control the rate of song speed." So now you know. He went into greater detail in the Youtube video's description.
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.