## 3 Results
### fNiRS: HbO Data  
Figure 4 displays group-mean beta values of the HbO data for each channel and condition, separately for each group. Channel-wise contrast analyses revealed no significant differences between conditions for all groups (\(p>0.05\), FDR-corrected). Similarly, RM-ANOVAs for the anatomical-driven ROIs yielded no significant differences between conditions or groups and no significant interactions (\(p>0.05\)). The data-driven ROI's selection, based on the channels with the highest beta-values, yielded three ROIs for the SO condition: Two ROIs covering primarily the right and left MTG (each ROI including four fNIRS channels), and one ROI (including two fNIRS channels) covering part of the right DLPFC. For the SIN condition, three slightly different ROIs were formulated: Two ROIs covering similar (but not identical) areas in the right and left MTG as the SO ROIs (each including three channels), and one ROI (including two channels) covering the left fusiform gyrus. All the data-driven ROIs are circled in Figure 4. In addition to these ROIs, high beta-values were revealed in the SIN condition for a single channel covering part of the right DLPFC. This channel was separately analyzed as is detailed bellow. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{2}{c}{**CI**} & \multicolumn{2}{c}{**NHV**} & \multicolumn{2}{c}{**NH**} \\ \hline CI11 & 6.75 & NHV11 & 0.74 & NH11 & \(-\)7.02 \\ \hline CI12 & \(-\)3.36 & NHV12 & \(-\)2.55 & NH12 & \(-\)8.14 \\ \hline CI13 & CE & NHV13 & \(-\)3.48 & NH13 & \(-\)9.62 \\ \hline CI14 & CE & NHV14 & \(-\)1.42 & NH14 & \(-\)9.62 \\ \hline \multicolumn{2}{c}{} & NHV15 & \(-\)3.56 & NH15 & \(-\)7.64 \\ \hline \multicolumn{2}{c}{} & \multicolumn{1}{c}{} & \(-\)2.14 & \multicolumn{2}{c}{\(-\)9.03} \\ \multicolumn{2}{c}{} & \multicolumn{1}{c}{} & \((1.64)\) & \multicolumn{2}{c}{\((1.35)\)} \\ \hline \hline \end{tabular}
\end{table} 
Table 4: _Cont._  
Figure 4: Mean beta values of the GLM analysis for the HbO data, separately for each condition and group. NH = normal-hearing participants who listened to natural stimuli (n = 15), NHV = normal-hearing participants who listened to vocoded stimuli (n = 15), CI = cochlear implant users (n = 14), SO = speech-only condition, SIN = speech-in-noise condition, NO = noise-only condition. The mean beta values in the four data-driven ROIs covering the MTG are shown in Figure 5a,b for each group. In the left ROI with the SO condition and in the right and left ROIs with the SIN condition, the largest mean beta values were demonstrated for the NH, smaller values were demonstrated for the NHV, and the smallest values were demonstrated for the CI. In the right ROI with the SO condition, similar beta values were observed for the NH and NHV, with smaller values for the CI group. Two-way RM-ANOVA was conducted for these four MTG ROIs with Condition (SO, SIN) and Side (right, left) as the within-subject variables and Group (NH, NHV, CI) as the between-subject variable. Results revealed a significant effect of Group [F]1, 41) = 4.339 \(p\) = 0.020, \(\eta^{2}\) = 0.175], with larger beta values only for the NH group compared to the CI group (\(p\) = 0.017). No significant differences were observed between the NHV group and the other two groups (\(p\) > 0.05). There were also no significant effects of Condition or Side, and no significant interactions. Figure 5: Mean beta values (+1 SE) for the four MTG clustered ROIs for (**a,b**): the NH, NHV and CI groups, and (**c,d**): NH, NHV, good CI, poor CI. NH = normal-hearing participants who listened to natural stimuli (n = 15), NHV = normal-hearing participants who listened to vocoded stimuli (n = 15), CI= cochlear implant users (n = 14), Good CI = CI users with SRTn < 0 dB (n = 6), poor CI = CI users with SRTn > 0 dB (n = 8), SO = speech-only condition, SIN = speech-in-noise condition. Asterisk = \(p\) < 0.05. Univariate analyses comparing the three groups were separately conducted for the right DLPFC ROI with SO and for the left fusiform gyrus ROI with SIN.