Active cancellation of occlusion: An electronic vent for hearing aids and hearing protectors

Jorge Mejia, Harvey Dillon, Michael Fisher

Research output: Contribution to journalArticlepeer-review


The occlusion effect is commonly described as an unnatural and mostly annoying quality of the voice of a person wearing hearing aids or hearing protectors. As a result, it is often reported by hearing aid users as a deterrent to wearing hearing aids. This paper presents an investigation into active occlusion cancellation. Measured transducer responses combined with models of an active feedback scheme are first examined in order to predict the effectiveness of occlusion reduction. The simulations predict 18 dB of occlusion reduction in completely blocked ear canals. Simulations incorporating a 1 mm vent (providing passive occlusion reduction) predict a combined active and passive occlusion reduction of 20 dB. A prototype occlusion canceling system was constructed. Averaged across 12 listeners with normal hearing, it provided 15 dB of occlusion reduction. Ten of the subjects reported a more natural own voice quality and an appreciable increase in comfort with the cancellation active, and 11 out of the 12 preferred the active system over the passive system.
Original languageEnglish
Pages (from-to)235-240
Number of pages6
JournalThe Journal of the Acoustical Society of America
Issue number1
Publication statusPublished - 2008


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