# Big-Delay Estimation for Speech Separation in Assisted Living Environments
## 5 Results
Figure 6 illustrates the boxplots of the measurements obtained for each mixture category. The categories correspond to 2-source, 3-source and 4-source mixtures. The PEASS toolbox [103] estimates the distortion, which is considered to be the error between the estimated source, \(\hat{s}_{\text{j}}[n]\), and the clean speech \(s_{\text{j}}[n]\) and given as  
\[\hat{s}_{\text{j}}[n]-s_{\text{j}}[n]=e_{j}^{\text{target}}[n]+e_{\text{j}}^{ \text{interference}}[n]+e_{\text{j}}^{\text{artifact}}[n]. \tag{47}\]  
The target distortion, \(e_{\text{j}}^{\text{target}}[n]\), indicates how many distortions (both attenuation and amplification distortions [108]) are added to the true target source during the filtering process. The measure of interference-related source energies present in the recovered utterance is denoted by \(e_{\text{j}}^{\text{interference}}[n]\) and \(e_{\text{j}}^{\text{artifact}}[n]\) is the measure of musical noise that degrades the demixed speech. Each recovered utterance, \(\hat{s}_{\text{j}}[n]\), is evaluated relative to the reference. The target signal, \(\hat{s}_{\text{j}}[n]\), is on a scale which ranges from 0 to 100 units, with higher scores indicating better quality of separation. As can be seen in Figure 6, Elevato-AdRess achieves a better Overall-Perceptual Score (OPS), Target-Related Perceptual Score (TPS), and Interference-Related Perceptual Score (IPS) performance than Elevato-DUET. Figure 6a shows that Elevato-AdRess outperforms Elevato-DUET in terms of the average OPS score, with a mean reconstruction improvement of 2 units for mixtures with two sources. This difference becomes more pronounced as the number of speech utterances in the mixtures increases, reaching a difference of 7 units for mixtures with four sources. Figure 6b highlights reduced distortions are experienced in the estimated utterances recovered by Elevato-AdRess. This is reflected by the average TPS scores, where Elevato-AdRess exceeds Elevato-DUET by 8 units in the case of two sources. For mixtures with four sources, the TPS score difference increases to 24 units. In Figure 6c, reduced energy leakage from interfering sources is observed in the estimates demixed by Elevato-AdRess compared to Elevato-DUET. For a two-source case, Elevato-AdRess outperforms Elevato-DUET by a score of 18 units and the latter lags behind the former by a score of 12 units when four sources are present in the mixture. The highest PEASS metric achieved by Elevato-AdRess resulted from reduced interference in the recovered utterance. The average IPS score exceeded 85 units and remained relatively stable, even as the number of constituent sources in the mixture increased, in contrast to Elevato-DUET, which showed a notable decline under similar conditions. In terms of artifact-related noise, Figure 6d reveals that Elevato-DUET achieves a higher Artifact-Related Perceptual Score (APS), indicating fewer artifacts compared to Elevato-AdRess. Specifically, Elevato-AdRess is outperformed by Elevato-DUET by an average score of 3 units in the two-source scenario. This difference increases slightly to 5 units in the case of four sources. This result aligns with the higher SNR observed for Elevato-DUET, as shown in Figure 7. A reasonable assumption is that discarding the overlapping frequency bin energies, the approach taken by Elevato-DUET, introduces significant distortion and artifact noise in the separated utterances. SNRs are typically high if they are greater than 5 dB, low if they are less than \(<\) dB, and completely unintelligible if they are less than 0 dB according to [3].