# Options for Performing DNN-Based Causal Speech Denoising Using the U-Net Architecture +
## 4 Experiment and Performance Evaluation
### Further Considerations of Loss Function in the STFT and STDCT Domains
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{\
\begin{tabular}{c} **Loss** \\ **Function** \\ **(\(a\),\(\beta\))** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Initial** \\ **SNR** \\ \end{tabular} } & \multicolumn{6}{c}{**Classical U-Net with CCABs**} & \multicolumn{6}{c}{**Advanced U-Net with GLFBs**} \\ \cline{3-14}  & & & **Resulting** & & & & & & & & & & & \\ \cline{3-14}  & & & **CSIG** & **CBAK** & **COVL** & **PESQ** & **STOI** & **Resulting** & **CSIG** & **CBAK** & **COVL** & **PESQ** & **STOI** **(\%)** \\ \hline \multirow{6}{*}{(0, 1)} & \(-2.5\) dB & 12.97 & 3.460 & 3.055 & 3.091 & 2.811 & 80.59 & 13.73 & 3.495 & 3.114 & 3.132 & 2.851 & 81.69 \\ \cline{2-14}  & \(2.5\) dB & 15.96 & 3.941 & 3.372 & 3.496 & 3.097 & 85.69 & 16.51 & 3.948 & 3.410 & 3.515 & 3.123 & 86.39 \\ \cline{2-14}  & \(7.5\) dB & 18.37 & 4.322 & 3.624 & 3.814 & 3.323 & 89.03 & 18.75 & 4.334 & 3.660 & 3.838 & 3.355 & 89.65 \\ \cline{2-14}  & \(12.5\) dB & 20.45 & 4.618 & 3.854 & 4.072 & 3.518 & 91.45 & 20.69 & 4.632 & 3.887 & 4.097 & 3.549 & 91.99 \\ \cline{2-14}  & Average & 16.94 & 4.085 & 3.476 & 3.618 & 3.187 & 86.69 & 17.42 & 4.102 & 3.518 & 3.646 & 3.220 & 87.43 \\ \hline \multirow{6}{*}{(0.5, 1)} & \(-2.5\) dB & 12.75 & 3.638 & 3.053 & 3.190 & 2.809 & 81.02 & 13.58 & 3.737 & 3.125 & 3.277 & 2.876 & 82.41 \\ \cline{2-14}  & \(2.5\) dB & 15.65 & 4.052 & 3.349 & 3.548 & 3.076 & 85.82 & 16.23 & 4.110 & 3.399 & 3.604 & 3.126 & 86.83 \\ \cline{2-14}  & \(7.5\) dB & 18.00 & 4.388 & 3.600 & 3.843 & 3.305 & 89.21 & 18.46 & 4.424 & 3.635 & 3.880 & 3.339 & 89.91 \\ \cline{2-14}  & \(12.5\) dB & 20.15 & 4.655 & 3.834 & 4.085 & 3.499 & 91.65 & 20.44 & 4.675 & 3.889 & 4.109 & 3.526 & 92.07 \\ \cline{2-14}  & Average & 16.64 & 4.183 & 3.459 & 3.666 & 3.172 & 86.92 & 17.18 & 4.237 & 3.504 & 3.718 & 3.217 & 87.81 \\ \hline \multirow{6}{*}{(0, 0.5)} & \(-2.5\) dB & 13.30 & 3.298 & 3.024 & 2.973 & 2.758 & 80.37 & 13.82 & 3.397 & 3.098 & 3.062 & 2.821 & 81.36 \\ \cline{2-14}  & \(2.5\) dB & 16.27 & 3.837 & 3.375 & 3.442 & 3.107 & 85.67 & 16.63 & 3.930 & 3.427 & 3.517 & 3.153 & 86.30 \\ \cline{1-1} \cline{2-14}  & \(7.5\) dB & 18.63 & 4.318 & 3.666 & 3.844 & 3.396 & 89.25 & 18.84 & 4.389 & 3.701 & 3.903 & 3.434 & 89.58 \\ \cline{1-1} \cline{2-14}  & \(12.5\) dB & 20.52 & 4.679 & 3.912 & 4.156 & 3.627 & 91.70 & 20.72 & 4.739 & 3.944 & 4.207 & 3.666 & 92.02 \\ \cline{1-1} \cline{2-14}  & Average & 17.18 & 4.033 & 3.494 & 3.604 & 3.222 & 86.75 & 17.50 & 4.114 & 3.542 & 3.672 & 3.269 & 87.32 \\ \hline \multirow{6}{*}{(0, 0.5)} & \(-2.5\) dB & 13.08 & 3.750 & 3.120 & 3.267 & 2.844 & 81.14 & 13.93 & 3.901 & 3.222 & 3.402 & 2.949 & 82.65 \\ \cline{1-1} \cline{2-14}  & \(2.5\) dB & 16.04 & 4.206 & 3.448 & 3.677 & 3.171 & 86.25 & 16.66 & 4.312 & 3.520 & 3.777 & 3.259 & 87.24 \\ \cline{1-1} \cline{2-14}  & \(7.5\) dB & 18.44 & 4.569 & 3.715 & 4.007 & 3.442 & 89.74 & 18.89 & 4.639 & 3.769 & 4.078 & 3.509 & 90.30 \\ \cline{1-1} \cline{2-14}  & \(12.5\) dB & 20.50 & 4.848 & 3.954 & 4.268 & 3.663 & 92.18 & 20.90 & 4.907 & 4.004 & 4.331 & 3.727 & 92.67 \\ \cline{1-1} \cline{2-14}  & Average & 17.01 & 4.343 & 3.559 & 3.805 & 3.280 & 87.32 & 17.59 & 4.440 & 3.629 & 3.897 & 3.361 & 88.21 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Performance comparison for the classical and advanced U-Nets in the STFT domain with four loss functions exploiting the power compression and trade-off between magnitude estimation and phase recovery. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{\ \begin{tabular}{c} **Loss** \\ **Function** \\ **Function** \\ **(\(a\),\(\beta\))** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **Initial** \\ **SNR** \\ \end{tabular}