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This paper introduces a new type of electret microphone with an excellent dynamic range (0-120 dB SPL) and excellent frequency response characteristics over the range of 20 Hz to 20 kHz. The fundamental concept behind the new microphone is the placement of a thin PTFE (Teflon) electret membrane inside the core of a toroidal coil. As the membrane vibrates in response to the sound, a very small magnetic field is created, is picked up by the coil, and is amplified by a superconducting quantum interference device (SQUID) or by a conventional FET amplifier. Analysis and experimental results show that this new transduction mechanism results in a microphone that, while physically larger than other microphones, has substantially better performance in high-bandwidth applications.