Creating a boundary microphone out of a mobile phone

At your risk.

First time I saw it was when Zhanna placed the mobile phone on top of the right side of the piano keyboard.

Apparently by placing the mobile phone this way, the mic capsule comes so close to the boundary (the wood of the piano) that it picks up mainly the main reflection of sound from wood (boundary mic principle), plus the vibration of wood itself.

Here are 2 recording of the same piano same day, different solo pianist (the person at the right side), different mobile phones, but one phone is held by hand, the other recording is by placing the phone (Galaxy A13) as described above.

 

Some more information on boundary microphones:

The Wikipedia article:

https://en.wikipedia.org/wiki/Boundary_microphone