Sonar-Operator Active Noise Reduction Insert-Earphone: Prototype Preliminary Test and Evaluation.

摘要

Evaluation of Commercial Off-the-Shelf (COTS) headset products confirmed our decision to press for development of high fidelity sensor operator earphones capable of removing low-frequency noise through active signal processing. The current research assesses a prototype Digital Noise Reduction (DNR) insert earphone device, with in-ear 2-way communications that, with minor modifications, can meet those requirements. Noise attenuation measurements show the prototype capable of greater than 32 dB reduction in airborne sound in the 1/3-octave bands from 50 Hz to 10kHz. This was achieved through microprocessor-controlled digital noise reduction, without needing further application of onboard active noise cancellation (ANC) processes. Frequency response, while adequate for speech, needs to be upgraded for use by sonar operators as was done on several ANC headsets. Given the capabilities of digital processing, this is a minor, though critical, issue.