Privacy with intelligibility—A novel electroacoustic solution

Abstract

The concept of electronic sound masking is a well-established and successful solution in helping to achieve adequate speech privacy either within or between office areas or similar spaces. In many instances, separate paging or voice-alarm systems are also installed. Whereas locating loudspeakers in the ceiling void or within a plenum assists sound diffusion and evenness of coverage, this also degrades speech intelligibility and causes significant nonlinear (frequency-dependent) transmission losses. Conversely, installing conventional loudspeakers directly into the ceiling can result in good intelligibility but poor sound diffusion, leading to uneven sound distribution and immediate localization of the loudspeaker as the sound source. The diffuse, substantially decorrelated and wide dispersion characteristics of the distributed mode loudspeaker suggests that systems employing this new class of device may simultaneously satisfy the requirements for both speech privacy and speech intelligibility. The paper presents the results of a study using a range of loudspeaker formats to establish whether these apparently opposing requirements can be achieved.