Recent progress in research on virtual sound barriers

A virtual sound barrier is an active noise control system that uses arrays of loudspeakers and microphones to create a practical size of quiet zone in a noise environment just like an acoustic barrier but without blocking air and light. This technology can be used to reduce sound radiation from noise sources or to reduce noise level around one or few person heads in noisy environments in many industrial and domestic situations. This paper introduces the history, principle and design methods of the virtual sound barriers first, and then describes recent progress in research on the systems, especially the application on power transformer noise radiation control from an enclosure. The paper is concluded by the limitations and future direction discussions of the virtual sound barriers