...
http://en.wikipedia.org/wiki/Acoustic_camera
Electret microphone
Charasteristics
Electret microphone is omnidirectional. This meas that it can hear from all directions. Transistor works as transducer in the heart of the electret microphone. Electret microphone
Sensitivity(- 46 ± 2.0, ( 0 dB = 1V / Pa ) at 1K Hz)
Transfer function of the Electret microphone is the electrical force gained on the diaphragm:
F≈(E_dc+E_ac )^2-(E_dc+E_ac )^2=4E_dc E_ac
Where
E_dc =
E_ac =
Source of charasteristics:
http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Sensors/Sound/CEM-C9745JAD462P2.54R.pdf
Material and manufacturing
...