# Interaural Coherence Estimation for Speech Processing in Reverberant Environment
## 3 Numerical Experiment and Results
### IC Estimation Performance Comparison with Conventional Method  
By comparing the proposed method with the conventional method, we tried to confirm the validity of the algorithm and assumption based on the quasi-steady interval proposed in this paper. Before applying the conventional method, the IC estimation performance depends on \(\alpha\) thus, we compared the performance of conventional method according to \(\alpha\) with that of the proposed method using the specific parameters determined from previous simulations. In this numerical experiment, MACtotal was also used to accurately compare the performance of estimation. MACtotal was calculated by applying the proposed method to 1680 speech samples of the test set using STFT with a 25-ms Hamming window, 10-ms hop length, and 512-point FFT according to the reverberant environment. The MACtotal for speech was averaged to compare the performance of the \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \multirow{2}{*}{**RT\({}_{60}\)**.} & \multicolumn{8}{c}{**Frequency**} \\ \cline{3-10}  & **0-1 kHz** & **1-2 kHz** & **2-3 kHz** & **3-4 kHz** & **4-5 kHz** & **5-6 kHz** & **6-7 kHz** & **7-8 kHz** \\ \hline \multirow{2}{*}{0.37 s} & \(L_{\rm T}\) & 9 & 7 & 7 & 7 & 7 & 7 & 7 & 7 \\ \cline{2-10}  & \(\beta\) & 0.70 & 0.85 & 0.70 & 0.75 & 0.70 & 0.75 & 0.60 & 0.65 \\ \hline \multirow{2}{*}{0.69 s} & \(L_{\rm T}\) & 9 & 9 & 9 & 9 & 7 & 9 & 9 & 9 \\ \cline{2-10}  & \(\beta\) & 0.90 & 0.95 & 0.95 & 0.95 & 1.00 & 0.85 & 0.80 & 0.80 \\ \hline \multirow{2}{*}{0.79 s} & \(L_{\rm T}\) & 11 & 11 & 11 & 9 & 9 & 9 & 9 & 9 \\ \cline{2-10}  & \(\beta\) & 1.00 & 1.00 & 1.00 & 1.00 & 1.00 & 1.00 & 1.00 & 1.00 \\ \hline \end{tabular}
\end{table} 
Table 2: Optimal \(L_{\rm T}\) and \(\beta\) according to the frequency intervals and reverberation environment using a 25-ms Hamming window, 10-ms hop length, and 512-point FFT. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \multirow{2}{*}{**RT\({}_{60}\)**.} & \multicolumn{8}{c}{**Frequency**} \\ \cline{2-10}  & **0-1 kHz** & **1-2 kHz** & **2-3 kHz** & **3-4 kHz** & **4-5 kHz** & **5-6 kHz** & **6-7 kHz** & **7-8 kHz** \\ \hline \multirow{2}{*}{0.37 s} & \(L_{\rm T}\) & 7 & 7 & 5 & 5 & 5 & 5 & 5 & 5 \\ \cline{2-10}  & \(\beta\) & 0.55 & 0.55 & 0.65 & 0.70 & 0.60 & 0.70 & 0.55 & 0.60 \\ \hline \multirow{2}{*}{0.69 s} & \(L_{\rm T}\) & 7 & 7 & 7 & 7 & 5 & 7 & 7 & 7 \\ \cline{2-10}  & \(\beta\) & 0.85 & 0.85 & 0.80 & 0.85 & 1.00 & 0.75 & 0.70 & 0.70 \\ \hline \multirow{2}{*}{0.79 s} & \(L_{\rm T}\) & 7 & 7 & 7 & 7 & 7 & 7 & 7 & 7 \\ \cline{2-10}  & \(\beta\) & 1.00 & 1.00 & 1.00 & 1.00 & 1.00 & 1.00 & 1.00 & 0.75 \\ \hline \end{tabular}
\end{table} 
Table 3: Optimal \(L_{\rm T}\) and \(\beta\) according to the frequency intervals and reverberation environment using a 64-ms Hamming window, 16-ms hop length, and 1024-point FFT. two methods numerically. By applying the proposed method in the same way as the conventional method, the averaged \(\text{MAC}_{\text{total}}\) was calculated according to \(\alpha\), and its results are represented by the solid lines in Figure 4. The results of applying the previously determined \(L_{\text{T}}\) and \(\beta\) to the proposed method are represented by the dotted lines. The averaged \(\text{MAC}_{\text{total}}\) was a low value when \(\alpha\) was close to zero and one, which means that the IC of reverberant speech was inaccurately estimated. A large \(\text{MAC}_{\text{total}}\) means a high IC estimation performance; therefore, \(\alpha\) for the maximum value of averaged \(\text{MAC}_{\text{total}}\), which is an indicator of overall performance used in determining \(L_{\text{T}}\) and \(\beta\), was the optimal value. It was 0.60 in 0.37 s of \(\text{RT}_{60}\), 0.50 in 0.69 s of \(\text{RT}_{60}\), and 0.25 in 0.79 s of \(\text{RT}_{60}\).