From Wikipedia
An electret microphone is a microphone whose diaphragm forms a capacitor (historically-termed a condenser) that incorporates an electret. The electret's permanent electric dipole provides a constant charge Q on the capacitor. Sound waves move the diaphragm, changing the capacitance C, which produces a corresponding voltage change across the capacitor of ΔV = Q/ΔC. The electret's constant charge eliminates the need for the polarizing power supply required for non-electret condenser microphones, though a preamplifier is typically incorporated to boost the audio voltage signal.
Questions people ask
Real questions from the Stack Exchange community – follow a link to read the discussion.
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