The spatial uniformity of an electronic sound masking system in an open-plan space

Abstract

An electronic sound-masking system reduces workers' distractions in open-plan spaces by utilizing an artificial broadband sound. The artificial sound should raise a background noise level spectrum to the targeted masking sound level uniformly over the entire area.Uneven distribution of the masking sound levels can cause unnecessary loud background noise or inefficient sound masking performance at the same time and in different locations. The ASTM E 1573-18 standard provides a procedure to quantify the uniformity of the masking sound but does not specify any acceptable degree of uniformity. Thus, this study aims to investigate the uniformity of the masking sound field in an open-plan space under varying room acoustic conditions. The acoustic measurement was carried out in an open-plan office with a measurement grid of 0.6 m. The spatial variation of the sound pressure levels was calculated with the measured one-third-octave band SPLs from 250 Hz to 4 kHz. The study also employed computer-aided acoustic simulation to find key design parameters, impacting the uniformity of the masking sound. The results show that the number of loudspeakers, a partition height, scattering, and absorption coefficients can significantly influence the spatial uniformity and speech privacy within the space. Finally, the results proposed an acceptable variation of the masking sound field by examining the Articulation Index (AI) change in the space.