Working on a related mic-building project (stethoscopes and the iPhone), I had a brainwave that it might be easier to essentially pipe the audio from the stethoscope head directly into the iPhone mics. About 90 minutes of MakerBot printing later, the first test was done. Though there were a few problems with the printing (tape is covering holes that ended up occurring), overall it works really well.
The next version will include an inner chamber to direct the sound to the mics better. Shrinkage was also less of an issue than with previous projects – a little tight on the sides but not the front/back. As a nice treat, the MakerBot ABS doesn’t seem to do any damage to the iPhone surface (knock on wood).
This sample is the stethoscope on my chest and clothes, then up against my neck, gulping, quiet talking, whispering, and ending with the stethoscope rubbed against my beard.