In this work, the authors present a comprehensive methodology for multizone sound field reproduction using specially designed speech masking filters. The masking filters are designed to maximise speech privacy and quality. Trade-offs between speech privacy and quality are shown to exist and parameters are provided in the methods to control those trade-offs. An accurate and precise formulation of grating lobes from spatial aliasing in multizone reproduction scenarios is provided and used to enhance the masking filters. The mathematical descriptions and thorough methodology are evaluated using simulations and a real world implementation of a multizone sound field reproduction system.
Using a planar array of microphones and loudspeakers, the authors show in this work a theoretical approach to actively suppressing the reflection of sound from boundaries, such as room walls. The filters that are proposed are applicable to real-time implementations and it is shown that the active absorption is similar to that of passive fibre panel absorption.
Using only two microphones, like those commonly found on mobile devices, we show in this work how to count the number of people talking in a meeting scenario. This paper has been presented at and published in the proceedings of the 2017 Asia Pacific Signal and Information Processing Association Annual Summit and Conference (APSIPA ASC) in Kuala Lumpur, Malaysia.
Ever wondered if you could cancel someones voice without the need for a physical wall or partition? In this work presented at ICASSP 2017 in New Orleans, USA, we investigate the possibilities of cancelling speech over a loudspeaker wall. The method is not limited to speech, in-fact, it works much better for periodic signals as the non-stationarity of speech degrades the performance.
Blindly counting the number of speech sources (talkers) in a meeting room can be a difficult task. This paper was presented at HSCMA 2017 at the Google Offices in San Francisco and shows how using coherent-to-diffuse ratios could allow real-time source counting.