## 4 Results and Discussion
The SegSNR is a quantitative criterion, which shows the improvement in the enhanced signal due to the percentage of the noise power elimination from the noisy signal, namely:  
\[\text{SegSNR}_{(dB)}=\frac{1}{K}\sum\limits_{i=0}^{R}10\log_{10}\left(\frac{ \sum\limits_{j=0}^{Q-1}\abs{S_{j}[n]}^{2}}{\sum\limits_{j=0}^{Q-1}\abs{S_{j}[ n]-Z_{j}[n]}^{2}}VAD_{i}\right) \tag{33}\]  
where \(S[n]\) and \(Z[n]\) are the clean and enhanced speech signals, respectively. The variable \(Q\) is the mean averaging value of the SNR for the output signal. The variable \(R\) is the number of only-speech frames and \(VAD\) is a speech detector, which is 1 for only-speech frames and 0 for only-noise frames. Therefore, the SegSNR is appropriate to show the speech enhancement performance. Many of the speech enhancement algorithms eliminate some part of the speech signals in addition to the noise frames, which decreases the speech perception for the enhanced signals. Then, three well-known qualitative criteria are considered in the evaluations. The first one is the PESQ, which is defined based on the standard ITU-T P.862 for qualitative evaluations of speech signals in mobile stations [4; 42]. In fact, the PESQ criteria is used in the numerical representation of qualitative evaluations for enhanced speech signals. The defined range for this criteria is \([-0.5\,4.5]\), where \(-0.5\) and \(4.5\) show the lowest and highest quality of the enhanced speech, respectively. Additionally, the results were compared with the MOS score criteria. These are qualitative criteria in telecommunication systems that represent the clarity, perception, and intelligibility of the enhanced signal. The MOS criteria are defined based on the standard ITU-T P.800 [5; 43] in telecommunication systems. The evaluation results based on the MOS criteria was implemented by the use of some volunteers, by listening to the enhanced signal, where \(1\) and \(5\) are the lowest and highest scores in this criteria, respectively. Table 3 shows the defined scores for the MOS criteria in the evaluations. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Rating** & **Quality (Standard ITU-T P.800)** & **Impairment** \\ \hline
5 & Excellent & Imperceptible \\
4 & Good & Perceptible but not annoying \\
3 & Fair & Slightly annoying \\
2 & Poor & Annoying \\
1 & Bad & Very annoying \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The numerical scores for the mean opinion score (MOS) criteria in the evaluation process. Finally, the last qualitative criteria for evaluations is the STOI. This criteria predicts the intelligibility of humans based on a series of cases. The speech intelligibility measurement is based on the existence of a series of pre-assumptions, but if the noisy signal is processed based on the time-frequency weighting, the final results are not trustable. The STOI is an objective intelligibility measurement, which represents the highest convolution value by the intelligibility of both noisy and weighted time-frequency noisy signals. In addition, the lowest and highest scores for the STOI criteria are 0 and 1, which represent the best and the worst enhancement performance, respectively. Firstly, the proposed method was evaluated on the white noise and then, the other colored noise were considered in the experiments. The proposed CNMA-SBAPA was evaluated on real and simulated data in comparison with the LMS, traditional APA, RLS, DB-MWF, and MNMF-MVDR algorithms. Figure 11 shows the time-domain and spectrum for the noisy and enhanced signals in the presence of white noise for SNR = 0 dB. As seen in these figures, the proposed CNMA-SBAPA method decreased more level of the noise with less distortion in comparison with other works. However, the numerical values are necessary for comparison. In the following, the experiments were evaluated with quantitative and qualitative criteria. Figure 11: _Cont._  
In the following, the proposed method was compared by numerical criteria with other previous works.