An adaptive signal processing system for active control of sound in remote locations

Adaptive active noise control (ANC) systems with single-channel structure create a silent point at the location of an error microphone. This silent point creates a zone of quiet surrounding itself, however, this zone has small dimensions. Moreover, the error microphone has to be located within the zone of quiet, limiting the effective space available in the zone of quiet. This paper develops a new adaptive signal processing system for ANC in a remote point, located far from the error microphone. Accordingly, the effective space of the zone of quiet can be extended. It is shown that an optimal controller for the creation of a remote silent point can be constructed by the series combination of a digital controller, called the remote controller, and an adaptive digital filter. The transfer function of the remote controller is derived based on the system model in the acoustic domain. A new update equation for the automatic adjustment of the adaptive digital filter is proposed. The validity of the results is discussed through different computer simulations.