An active noise barrier system optimized for reducing outdoor stationary noise

Active Noise Control (ANC) techniques are based on the sound emission of an antiphase signal in order to cancel a noise produced by a primary source and are efficient at low frequencies. One of the most promising open space application fields for ANC techniques is the development of Active Noise Barriers (ANB), where the control system is paired with a traditional noise barrier. One of the main limits of traditional barriers is that their efficiency is low in the lower frequency range (less than 500 Hz). In this paper we analyze the properties of a low-cost ANB system able to efficiently operate on stationary pure-tone low-frequency noise produced in an electrical station, due to, eg. transformers or reactors. The prototype we realized shows a remarkable efficiency in the far field, with additional abatements up to 15 dB with respect to a traditional noise barrier.