  Several speech processing systems have demonstrated considerable performance
improvements when deep complex neural networks (DCNN) are coupled with
self-attention (SA) networks. However, the majority of DCNN-based studies on
speech dereverberation that employ self-attention do not explicitly account for
the inter-dependencies between real and imaginary features when computing
attention. In this study, we propose a complex-valued T-F attention (TFA)
module that models spectral and temporal dependencies by computing
two-dimensional attention maps across time and frequency dimensions. We
validate the effectiveness of our proposed complex-valued TFA module with the
deep complex convolutional recurrent network (DCCRN) using the REVERB challenge
corpus. Experimental findings indicate that integrating our complex-TFA module
with DCCRN improves overall speech quality and performance of back-end speech
applications, such as automatic speech recognition, compared to earlier
approaches for self-attention.
