Lecture
This lecture covers the construction and operation of capacitive microphones, focusing on the variation of capacitance as the relevant quantity for measurement. It explains the construction of a capacitive microphone, the concept of electret microphones, and the presence of electrets allowing quasi-permanent polarization. The lecture also discusses the special circuit for electret microphones, including the need for a power supply to recharge them, and the advantages and disadvantages of using electret microphones.