> I think I might experiment with some material of some type underneath the
> microphone before I put the face plate on.
> I wonder if a little piece of rubber like a piece of tire inner-tube would
> help filter out the sound of the hard-drive spin-up when using the
> internal Microphone?

A piece of tube (or other seal against the interior) may help to shield
airborne sound coming from the box itself, but I don't think this will help
much.
Probably most of the noise is coming from structure-borne sound, e.g.
vibrations propagating to the microphone. You'd have a hard time fighting
this. It would require to take the mic off the PCB, attach it with
lightweight flexible wires instead, add some mass to it, and cushion it into
very soft material with some damping. There's just not enough space.

The construction I described looks pretty much like an external mic, did you
figure?

Jörg

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