Wave-domain adaptive filtering: acoustic echo cancellation for full-duplex systems based on wave-field synthesis

For high-quality multimedia communication systems such as teleconferencing or virtual reality applications, multichannel sound reproduction is highly desirable. While progress has been made in stereo and multichannel acoustic echo cancellation (MC AEC) in recent years, the corresponding sound reproduction systems still imply a restrained listening area ('sweet spot'). A volume solution for spatial sound in a large listening area is offered by wave field synthesis (WFS) or by ambisonics, where arrays of loudspeakers generate a prespecified sound field. However, before this new technique can be utilized for full-duplex systems, an efficient solution to the MC AEC problem has to be found. This paper presents a novel approach that extends the current state of the art of MC AEC and transform-domain adaptive filtering by reconciling the flexibility of adaptive filtering and the underlying physics of acoustic waves in a systematic and efficient way. To achieve this, the new framework of wave-domain adaptive filtering (WDAF) exploits the spatial information provided by densely sampled contours for both recording and reproduction. Experimental results with a 32-channel AEC verify the concept for both simulated and actually measured room acoustics.