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Firstly, you will need an amplifier which can work with different types of microphones .. picture 1.
As a "voice" filter you can consider a combination of passive and active LPFs (Low Pass Filter) .. picture 2.
As you don't need much gain in this stage, replace 680kΩ resistor with ≈10kΩ ..
This filter has been calculated for "telephone" band, which is ≈300Hz-3kHz ..
470µH RF choke (inductor) is sold as off-the-shelf item and can be obtained for less than $0.5, for example from here:
**broken link removed**
If you are worried about this inductor you can replace it by, say, 100-470Ω resistor, which will be not as effective as an inductor, but should work satisfactorily ..
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