Noise-Cancelling Fiber-Optic Microphone

Intelligible Voice communication in aviation systems is critical for efficient and safe performance. This work will develop a noise cancelling fiber optic microphone that can be used in electrically and acoustic noisy environments. Two pressure fiber optic microphones (FOM), a lens FOM and a shutter FOM, will have their acoustic cavities designed so that they are noise cancelling. The difference in phase and arrival time between sounds generated close to the microphone and those generated farther away will be exploited to achieve the noise cancelling performance. Both microphones are extrinsic, intensity modulated fiber optic pressure microphones using multimode fibers. By designing the acoustic cavity of the transducer so that the deflection of the diaphragm is dominated by sounds produced near the front of the microphone the microphone becomes noise cancelling.