Open loop active control of noise through open windows

Abstract

Noise propagating through open windows raises one major concern of livability in metropolises, where residential buildings and arterial roads are densely constructed. Active noise control (ANC) is a possible technique to improve the current situation. Usually, ANC systems adopt the closed-loop control, where the quietness after control is continuously monitored by error microphones. However, ANC systems that attenuate noise propagating through open windows should ideally avoid the use of error microphones for the ease of implementation and maintenance. Furthermore, as open windows are commonly larger than the wavelength of the incident noise, multichannel ANC systems are necessary. Therefore, they result in computational burdens that cannot be handled by low-cost hardware platforms. This paper formulates the ANC system for open windows as a spatial sampling and reconstruction problem, and demonstrates that controlling noise propagating through open windows leads to global reduction of noise levels in the room. Both centralized and decentralized open-loop control filters are feasible in dealing with broad-band noise frequencies.