# An Efficient Multistage Approach for Blind Source Separation of Noisy Convolutive Speech Mixture
## 4 Results and Discussion
### Subjective Evaluation  
In the case of subjective evaluation, listening tests were performed to verify the simulation results obtained in Tables 5-8. Five participants took part in the subjective evaluation experiments (two female, three male), where all the listening participants have normal hearing ability. Every listener was guided to mark a score from integer value 1 (estimated speech signals not audible) to integer 5 (estimated speech signals audible) of the extracted source speech signals from the noisy convolutive mixture. The listener listened to the original signal and the enhanced speech signals separated from the noisy reverberant mixtures using the two proposed models. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline  & \multicolumn{2}{c}{**Multivariate**} & \multicolumn{2}{c}{**Student’s T**} & \multicolumn{2}{c}{**Generalized**} & \multicolumn{2}{c}{**Proposed Model**} \\  & \multicolumn{2}{c}{**Gaussian**} & \multicolumn{2}{c}{**Distribution**} & \multicolumn{2}{c}{**Gaussian**} & \\
**RT** & \multicolumn{2}{c}{**Source Prior**[31]} & \multicolumn{2}{c}{**Source Prior**[42]} & \multicolumn{2}{c}{**Source Prior**[32]} & \\
**(ms)** & \(\Delta\)**SDR S\({}_{1}\)** & \(\Delta\)**SDR S\({}_{2}\)** & \(\Delta\)**SDR S\({}_{1}\)** & \(\Delta\)**SDR S\({}_{2}\)** & \(\Delta\)**SDR S\({}_{1}\)** & \(\Delta\)**SDR S\({}_{2}\)** & \(\Delta\)**SDR S\({}_{1}\)** & \(\Delta\)**SDR S\({}_{2}\)** \\ \hline
40 & 10.86 & 6.32 & 6.30 & 2.50 & 10.85 & 6.35 & 10.97 & 6.43 \\
80 & 2.38 & 2.52 & 4.34 & 2.07 & 4.55 & 2.62 & 4.87 & 3.14 \\
120 & 2.11 & 1.81 & 3.23 & 1.97 & 4.09 & 2.12 & 4.29 & 2.53 \\
160 & 1.72 & 1.56 & 1.19 & 1.16 & 3.82 & 2.06 & 3.91 & 2.39 \\
200 & 1.40 & 1.19 & 1.05 & 0.38 & 2.46 & 1.24 & 2.76 & 1.74 \\ \hline \end{tabular}
\end{table} 
Table 4: Average RT results for the second proposed model shown in Figure 2 with variable RT for multistage BSS models having different source priors. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline  & \multicolumn{2}{c}{**Multivariate**} & \multicolumn{2}{c}{**Student’s T**} & \multicolumn{2}{c}{**Generalized**} & \multicolumn{2}{c}{**Proposed Model**} \\  & \multicolumn{2}{c}{**Gaussian**} & \multicolumn{2}{c}{**Distribution**} & \multicolumn{2}{c}{**Gaussian**} & \\
**SNR** & \multicolumn{2}{c}{**Source Prior**[31]} & \multicolumn{2}{c}{**Source Prior**[42]} & \multicolumn{2}{c}{**Source Prior**[32]} & \\
**(dB)** & \(\Delta\)**SDR S\({}_{1}\)** & \(\Delta\)**SDR S\({}_{2}\)** & \(\Delta\)**SDR S\({}_{1}\)** & \(\Delta\)**SDR S\({}_{2}\)** & \(\Delta\)**SDR S\({}_{1}\)** & \(\Delta\)**SDR S\({}_{2}\)** & \(\Delta\)**SDR S\({}_{1}\)** & \(\Delta\)**SDR S\({}_{2}\)** \\ \hline \(-2\) & 5.76 & 4.48 & 3.79 & 5.39 & 5.81 & 4.67 & 5.87 & 4.51 \\
0 & 4.37 & 3.74 & 3.44 & 2.86 & 4.39 & 3.38 & 4.53 & 3.87 \\
2 & 3.86 & 3.34 & 3.37 & 2.56 & 3.90 & 2.68 & 3.96 & 3.52 \\
4 & 3.45 & 2.83 & 2.80 & 2.13 & 3.57 & 2.41 & 3.61 & 2.85 \\
6 & 2.34 & 2.18 & 2.37 & 1.02 & 2.40 & 1.95 & 2.43 & 2.47 \\
8 & 1.79 & 1.49 & 1.40 & 0.35 & 1.90 & 1.36 & 2.05 & 1.70 \\
10 & 0.70 & 1.19 & 0.63 & 0.11 & 0.81 & 1.22 & 1.02 & 1.45 \\ \hline \end{tabular}
\end{table} 
Table 3: Average SNR results for the second proposed model shown in Figure 2 with variable SNR for multistage BSS models having different source priors. The same speech signals were chosen for both objective evaluation and subjective listening analysis in these experiments. In the multistage model presented in Figure 1, the values of the parameters for window size, NFFT, and RT were set to 512, 1024, and 100 msec. The SNR value was varied from \(-2\) to 10 dBs. The score marked by the participants is based on the cleanness of the extracted signals from the convolutive mixture containing