Communications Headset Augmentation via Active Noise Cancellation: Attenuation and Speech Intelligibility Performance

Abstract

Active noise cancellation (ANC) techniques utilize electronic circuitry to provide a phase-inverted sound wave, or “anti-noise,” to physically cancel the energy in an offending noise. This technique, originally used for abatement of noise in sound fields, has recently been refined and adapted to headset communications systems to 1) improve the speech/noise (S/N) ratio at the ear, and 2) reduce the noise exposure threat to hearing. ANC poses several important human factors issues encompassing speech intelligibility performance, attenuation performance, reliability and maintainability, and appropriateness of application to specific noise problems, all of which are addressed briefly in this paper. Also discussed is an experiment using a Bose Aviation Headset in its ANC mode, a Bose Aviation Headset in its non-active mode, and a conventional (non-ANC) David Clark H10-76 Headset. The Bose ANC unit required a significantly higher S/N ratio in tank and pink noise environments than the two passive headset systems to maintain equal intelligibility at a 70% level, in part due to its stronger noise reduction and a higher required speech level. In regard to hearing protection performance, the ANC device exhibited a distinct advantage, resulting in lower projected OSHA daily noise doses than either passive headset, with the largest increment in protection occurring in the low frequency-biased tank noise.