  Signal extraction from a single-channel mixture with additional undesired
signals is most commonly performed using time-frequency (TF) masks. Typically,
the mask is estimated with a deep neural network (DNN), and element-wise
applied to the complex mixture short-time Fourier transform (STFT)
representation to perform the extraction. Ideal mask magnitudes are zero for
solely undesired signals in a TF bin and undefined for total destructive
interference. Usually, masks have an upper bound to provide well-defined DNN
outputs at the cost of limited extraction capabilities. We propose to estimate
with a DNN a complex TF filter for each mixture TF bin which maps an STFT area
in the respective mixture to the desired TF bin to address destructive
interference in mixture TF bins. The DNN is optimized by minimizing the error
between the extracted and the ground-truth desired signal allowing to learn the
TF filters without having to specify ground-truth TF filters. We compare our
approach with complex and real-valued TF masks by separating speech from a
variety of different sound and noise classes from the Google AudioSet corpus.
We also process the mixture STFT with notch-filters and zero whole time-frames,
to simulate packet-loss during transmission, to demonstrate the reconstruction
capabilities of our approach. The proposed method outperformed the baselines,
especially when notch-filters and time-frame zeroing were applied.
