Need to LEARN details on microphone diaphragms...

[Externet]

Good day.

Sound waves as speech make a dynamic microphone diaphragm vibrate. The waves hitting the ‘exposed’ side of the diaphragm make it to vibrate because has a minimal mass. If the diaphragm was massive, it would not perform well as a microphone.

The back side of the diaphragm can be exposed to the same vibrations as the front, or be encapsulated shielded from being exposed to the vibrations.

If the back side is not shielded, the motion of the diaphragm can have cancellation as vibrations push simultaneously in-phase to both sides yielding little or no movement.

If the rear of the diaphragm is enclosed and not exposed to the front-hitting vibrations, cancellation disappears and a signal performs properly sensed.

If the rear of the diaphragm is hermetic, not vented, a back side chamber ‘damping’ effect attenuates the signal somewhat.

A dynamic diaphragm held unsupported in mid air yields a minimal response to vibrations as has no reference to a fixed anchoring frame.  A diaphragm must be firmly held to a more massive frame of reference that does not vibrate in an appreciable magnitude. A detail mostly overseen.

Please mark what is right and what is wrong above.

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If a microphone must work fitted inside a hermetic capsule to protect it from harsh environment, and still perform reasonably well, the encapsulation should be

- flexible like silicone, polyethylene film ?

- rigid as aluminium foil ?

- have two separate chambers; one for the front of the diaphragm, another for its rear or a single ?

- the microphone itself should have its back vented to inside of the capsule ?

 

-This is about dynamic microphones; nothing is about electret condenser microphones-