An Experimental Study on Virtual Sound Barrier Performance in Workplaces

Abstract

Virtual sound barrier (VSB) represents an array of loudspeakers and microphones forming an acoustic barrier to create a quiet zone without blocking light and air circulation. Although the concept of VSB has been proposed for many years, practical applications are still rare due to its performance and cost. This chapter explores two application scenarios of implementing VSB in workplaces: one is an eight-channel circular VSB system in a small room to create a quiet zone and the other is an eight-channel planar VSB system mounted to the door of the small room to prevent the outside noise from propagating inside. For the circular VSB system, the loudspeakers are uniformly placed along a circle with a diameter of 1.4 m to create a quiet zone with a diameter of 0.8 m. The experimental results show that the system is effective in reducing the low-frequency noise from 100 Hz to 250 Hz, and the noise reduction can reach 8 dB at 100 Hz. For the planar VSB system, the loudspeakers are placed at the door to reduce the noise propagating from the outside to inside. The experimental results show that the low-frequency noise below 250 Hz is effectively reduced by up to 6 dB at 80 Hz. These results demonstrate the feasibility of VSB for blocking low-frequency noise propagation, but further improvements are needed at higher frequencies above 400 Hz.