Have music control a device with sine wave and frequency?
Whilst I was using a TENS unit (electric muscle stimulator) and was messing with the frequency and pulse width controls, I thought to myself, "What if I would redesign this device, so that I could plug it into my mp3 player and it control the frequency and pulse width so I could literally feel the music?" After long though, and looking to see if such a device existed (None that I could find.) I came up with nothing. Now my question is, how could I design such a device that would take in standard audio, and give a pulse width and frequency output? I would assume I would use a pulse width modulator (PWM) for the first part, but what about the frequency? And how would I make this as one unit? I am a complete novice at sine waves, frequency, audio, and things in that area, and I find the best way to learn is do a project involving it. So would anyone have an idea how such a device could be designed? Link, circuit diagrams, and tips are all gladly excepted.