How to loopback MIC and Earpiece?

[tony_lth]

In China, there are some very cheap ways to test MIC.
The system have a standard speaker, after linking a MIC, and the MIC just points to the speaker.
And the instruments can test the MIC performance with such a simulation system.
The cost is only 180 RMB. Very interesting solution.

 

[c_mitra]

In China, there are some very cheap ways to test MIC....

That is still the standard solution.

You stick a small magnet with a small rod with the voice coil and the magnet moves within a small coil that acts as a displacement sensor. The output of this coil is used as a feedback to ensure that the motion of the voice coil is accurately sinusoidal. Then you can produce a perfect sine wave at any given frequency and use that to test your microphone.