(Multichannel) Acoustic Echo Cancellation and Postfiltering
If a system or device operates in handsfree mode, acoustic coupling between its loudspeaker and microphone can occur: When the so-called far-end speaker’s signal is played via the loudspeaker (or multiple loudspeakers) on the other side, the microphone on that side might capture the respective signal(s) again. This is audible to the far-end speaker as an acoustic echo and can hinder proper communication. To avoid this issue, we perform research on traditional, hybrid, and purely neural network-based learned acoustic echo cancellation approaches [2, 3]. They remove the disturbing acoustic echo component and provide an ideally echo-free microphone signal. A typical final stage during speech enhancement is a so-called postfilter which is often applied to the outgoing microphone signal in the frequency domain [3, 4]. Allowing for a frequency-dependent modification of the signal, a postfilter can be used to perform residual echo suppression, noise reduction, speech reconstruction, or equalizing.
 M. Strake, B. Defraene, K. Fluyt, W. Tirry, and T. Fingscheidt, “INTERSPEECH 2020 Deep Noise Suppression Challenge: A Fully Convolutional Recurrent Network (FCRN) for Joint Dereverberation and Denoising,” in Proc. of INTERSPEECH, Shanghai, China, Oct. 2020,pp. 2467–2471.
 J. Franzen, E. Seidel and T. Fingscheidt, "AEC in A Netshell: on Target and Topology Choices for FCRN Acoustic Echo Cancellation," in Proc. of ICASSP, Toronto, Canada, Jun. 2021, pp. 156-160.
 E. Seidel, J. Franzen, and T. Fingscheidt, “Y2-Net FCRN for Acoustic Echo and Noise Suppression,” in Proc. of INTERSPEECH, Brno, Czechia, Sep. 2021, pp. 1–5.
 J. Franzen and T. Fingscheidt, “An Efficient Residual Echo Suppression for Multi-Channel Acoustic Echo Cancellation Based on the Frequency-Domain Adaptive Kalman Filter,” in Proc. of ICASSP, Calgary, AB, Canada, Apr. 2018, pp. 226–230.