Our microphone brick converts acoustic vibrations into electrical signals. The microphone can be described as the opposite of the speaker. Many microphones use the variable capacitance property of capacitors to convert the pressure waves of sound into electrical vibrations. Since our microphone contains a field effect transistor for amplification, care must be taken to ensure the correct polarity (see + and -). The frequency spectrum ranges from 20-20,000Hz. The sensitivity is approx. 5-10mV/Pa.