Low-Complexity Multi-Microphone Acoustic Echo Control in the Short-Time Fourier Transform Domain

Many modern communication and smart devices are equipped with several microphones, in addition to one or more loudspeakers. Each microphone not only acquires sounds produced in the near-end room, i.e., desired near-end speech, background noise, and other interferences, but also a far-end signal that is reproduced by the loudspeaker(s). This particular type of acoustic coupling, commonly denoted as acoustic echo, can be reduced in a distortionless manner by employing multi-microphone acoustic echo cancellation (MM-AEC) techniques. However, under noisy conditions, the performance of AEC is limited by the echo-to-noise ratio, and additional echo reduction is needed. Further, to ensure high-quality end-to-end communication in noisy environments, background noise has to be reduced as well. To achieve the latter, multi-microphone speech enhancement techniques, such as beamforming (BF), are often used as they are capable of reducing undesired signal components while causing little distortion to the desired near-end speech. In spite of its high computational cost, the most effective solution to reduce acoustic echoes and background noise is to cascade MM-AEC and BF. In this work, a low-complexity multi-microphone echo controller is introduced, which not only combines low-complexity MM-AEC with BF, but also integrates residual echo reduction into the beamformer design.