The effect of remote microphone technique and head-tracking on local active sound control

Abstract

Local active sound control can potentially attenuate higher frequency noise, above about 300 Hz, at targeted regions, such as human’s ears. Specifically, for a single channel system in a diffuse field, the zone of quiet within which at least 10 dB of attenuation is achieved is formed around the error microphone with a diameter of about one-tenth of the acoustic wavelength. In practice, direct installation of physical error microphones at the ears seems impossible. Therefore, the signals from virtual error microphones at the targeted control regions should be estimated from physical monitoring microphones. Moreover, the stability and performance of a real time adaptive active control system is mainly determined by differences between pre-calculated and actual acoustic responses, which can be changed by head movements. This paper presents the integration of the remote microphone technique and a head tracker into local active control in order to improve its performance and stability. First of all, it was investigated through experiments and simulations that remotely installed monitoring microphones with an observation filter can estimate the virtual error microphone signals. In addition, it was shown that as the head tracker can update the pre-calculated responses of moved head positions, the stability and performance of the local active control system with the remote microphone technique can be improved.

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Identifiers

ORCID for Jordan Cheer: orcid.org/0000-0002-0552-5506

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