Fun app
 

Just downloaded this MultiMediaStudio doing the setup on my phone and then later going to calibrate with some sources here at the office.

Heres a youtube video as well.

<iframe width="560" height="315" src="http://www.youtube.com/embed/qJcOq5sLxPo" frameborder="0" allowfullscreen></iframe>

How much??

$4.49 I deal with this sort of stuff for my job so it's worth it. Heck I could probably even expense it.
I recommend checking out the list of phones on their website. Some don't have much sensitivity, but mine so happens to be one of the most sensitive.