Watch this video and see if you can see how it works:
The Kaiser Baas product, called the ‘CONTACT’, is just under $60.
My first thought was that it senses the vibration, or has a little microphone built in. But no, apparently it uses something called ‘near field audio’. This doesn’t even have a Wikipedia entry yet. It seems that the gadget picks up the sound by means of good old fashioned magnetic induction from the speaker in the phone. (Remember the suction cap gadgets by which you could record a call from an old-fashioned
That makes it pretty much independent of the model — so long as you put it in the right place for the unit’s built in speaker to be detected by the induction coil. Of course it won’t work with an iPod Classic, Nano or Shuffle (no speakers in them to induce any currents). And the sound may very depending on the source unit since they may have shaped frequency responses to optimise the performance of their pitiful inbuilt speakers, and this is presumably different from model to model.
Still, an interesting concept. I’ll see if I can get ahold of one to review.