Combining Artificial and Natural Background Noise in Personal Audio Systems

Abstract

Personal audio systems are designed to deliver spatially separated regions of audio to individual listeners. This paper presents a method for improving the privacy of such systems. The level of a synthetic masking signal is optimised to provide specified levels of intelligibility in the bright and dark sound zones and reduce the potential for annoyance of listeners in the dark zone by responding to changes in ambient noise. Results from a simulated personal audio system indicate that less acoustic contrast is required to produce the same level of privacy when artificial masking is included in the system design, compared with relying on the masking effect of background noise alone. As privacy requirements become more challenging, the advantage gained by incorporating artificial masking increases.

Combining background noise and artificial masking to achieve privacy in sound zones

“…The present article describes a method for specifying the technical requirements of a sound zoning system based on the predicted speech intelligibility in each listening zone and the masking effect of the environmental background noise present in the listening space, which has not been considered in previous work. The analysis presented in this article significantly expands on previous work by the authors [16] through the use of ambient noise recordings from a range of typical environments, rather than assuming a single, speech-shaped background noise spectrum and thus expands the practical relevance of this study. The proposed approach is based on the recognition that in spaces where privacy is a concern, there is also likely to be additional sources of noise, for example, due to the voices and activity of other people sharing the space.…”

Providing Spatial Control in Personal Sound Zones Using Graph Signal Processing

“…This effect can be disturbing for a user located in the dark zone because of the sudden energy changes, which can also affect the privacy in the dark zone. Authors in [12] propose to use a masker signal on the residual interference in the dark zone in order to reduce the intelligibility, and consequently, improve the privacy between zones. However, if the energy distribution in the dark zone is not uniform, the masking signal is only able to reduce the intelligibility in the spatial points where the energy is close to the mean or lower.…”