Cartilage conduction is a sound transmission pathway in which vibrations of the auricular cartilage deliver acoustic information to the eardrum. Unlike conventional earphones, cartilage conduction devices do not occlude the ear canal, so it makes the output signals masked by environmental noises. To address this issue, the implementation of Active Noise Control (ANC) which presents the secondary source in the cartilage conduction pathway is required. Although our studies have conducted computational simulations for the new ANC, noise canceling effects in actual sound fields are not investigated. In this study, we developed a cartilage conduction ANC system with the Filtered-X Least Mean Square algorithm in an anechoic chamber. A Digital Signal Processor was introduced to control the reference and error signals, and the error signals were obtained by an auricular model able to simulate the cartilage conduction. As results, these setups could reduce pure tones in lower frequencies than 1750 Hz, which corresponded the maximum output of the current cartilage conduction device. And the proposed system achieved approximately 3 and 6 dB reductions in broadband (100–1000 Hz) and narrowband noises (300–600 Hz), respectively. Our trials form the basis for the open-ear noise cancelation of ANC cartilage conduction devices.
Ueda et al. (Wed,) studied this question.