# Big-Delay Estimation for Speech Separation in Assisted Living Environments
## 5 Results
In general, the SNRs of the separated speech utterances decrease with an increase in the number of constituent sources in the mixture, where the SNR between the clean utterance, \(s_{\parallel}[n]\), and the recovered utterance \(\hat{s}_{\parallel}[n]\), is defined as  
\[\text{SNR}=10\log_{10}\frac{\big{|}|s_{\parallel}[n]|\big{|}_{2}^{2}}{\big{|}| s_{\parallel}[n]-\hat{s}_{\parallel}[n]|\big{|}_{2}^{2}}. \tag{48}\]  
Figure 4:0 (**a–d**) PEASS scores: the OPS, TPS, IPS, and APS scores are used to compare the performance of Elevato-AdRess and Elevato-DUET relative to the Ideal-Binary Mask (IBM). The PEASS scores are compared as a function of the number of sources in each mixture, which increases from two to four. Boxplots are used to summarize the performance. Elevato-AdRess obtains a better Overall-Perceptual Score (OPS), Target-Related Perceptual Score (TPS), and Interference-Related Perceptual Score (IPS) compared with Elevato-DUET. In Figure 7, it can be observed that Elevato-DUET improved SNR performance compared to Elevato-AdRess by a measure of 4.9, 4.5, and 4.13 dB for the two, three, and four mixtures cases, respectively. Higher quality speech-utterance separation does not necessarily mean that high intelligibility is achieved [108; 109]. A good speech demixing and enhancement algorithm must preserve intelligibility while improving the quality of separation. To evaluate intelligibility, the PESQ Mean Opinion Score (MOS) [104] intelligibility assessment is used. These scores range from \(-0.5\) to 4.5 units with scores below 1 unit indicating unintelligible speech and higher scores reflecting better intelligibility. Comparing an utterance with itself gives a MOS score of \(\geq\)4 units. Figure 8 quantifies the intelligibility of the demixed speech utterances. For a mixture of two sources, \(J=2\), Elevato-AdRess achieves a NarrowBand (NB) MOS score of 1.4 units higher than Elevato-DUET. This difference increases to 1.73 units in a four-source scenario, \(J=4\), as shown in Figure 8 (left). In this scenario, Elevato-AdRess achieves better performance than the IBM by 0.3 units. Figure 8 (middle) illustrates that in terms of the Listening Quality Objective (LQO) score, Elevato-AdRess gives better performance than Elevato-DUET and IBM by 0.57 units for the two-source case. This improvement rises to 1.1 units when there are \(J=4\) sources in the mixtures. Finally, Figure 8 (right) highlights the WideBand (WB) MOS scores, which extend the NB evaluation to account for broader frequency ranges, further demonstrating the superior performance of Elevato-AdRess. Note that the standard separation quality achieved by Elevato-AdRess is largely preserved, as the number of constituent sources in the speech mixtures increases from two to four. This demonstrates the robustness of Elevato-AdRess, as it remains relatively unaffected by the increase in number of sources in the mixture. Figure 4:1 Boxplots of the SNR of the sources recovered by Elevato-AdRess and Elevato DUET from two, three and four source mixtures. The Ideal-Binary Mask (IBM) is given as the benchmark demixing algorithm. The SNR of the separated speech utterances decreases as the number of sources in the mixture increases. In summary, Elevato-DUET demonstrates better SNRs for the recovered sources than Elevato-AdRess.