Figure 1
When aided with BCDs, mean SRTs (SD) for the SSD group were −6 (1.83) dB SNR in the Co-located condition, −5.57 (3.31) dB SNR in the SeparatedS0NNH condition, and −8.86 (3.02) dB SNR in the SeparatedS0NSSD condition. A significant effect of the conditions was also found on SRTs for the SSD group using BCDs (F=3.94, p<0.05); SRTs in the SeparatedS0NSSD condition were the lowest followed by SRTs in the SeparatedS0NNHcondition, and SRTs were largest in the Co-located condition. Paired t-tests revealed significant differences between SRTs for the SSD group with and without BCDs in all three test conditions (all p<0.05).
For NH listeners, the mean SRTs (SD) in the Co-located and Separated conditions were −6.57 (0.79) dB SNR and −9.43 (1.27) dB SNR, respectively, and there was a statistically significant difference between these two conditions (paired t-test, t=8.40, p<0.05; Figure 1). To further investigate the difference in SRTs between patients with SSD and their age-related NH counterparts, independent t- tests were used and significant differences were revealed between the following conditions: (a) co-located: unaided vs NH, −4.14 (1.95) dB SNR vs −6.57 (0.79) dB SNR, t=3.05, p<0.05; (b) SeparatedS0NNH: unaided vs NH, −2.43 (2.76) dB SNR vs −9.43 (1.27) dB SNR, t=6.09, p<0.05; (c) SeparatedS0NNH: aided vs NH, −5.57 (3.31) dB SNR vs −9.43 (1.27) dB SNR, t=2.88, p<0.05; (d) SeparatedS0NSSD: unaided vs NH, −7.14 (1.86) dB SNR vs −9.43 (1.27) dB SNR, t=2.68, p<0.05.
Figure 2 displays the relationship between SRTs in Co-located and two Separated conditions for patients with SSD and NH listeners. The point on the grey dashed diagonal line indicates no difference in SRTs between the Co-located and Separated conditions. The point clustered above the diagonal line suggests a higher SRT in the Co-located listening condition. Linear regression analysis revealed a significant positive correlation between the SRT in the Co-located and SeparatedS0NSSD conditions for patients with SSD when aided with BCDs (r2=0.67, p<0.05). The results demonstrated that patients with lower SRTs in the Co-located condition were more likely to perform well in the SeparatedS0NSSD condition when fitted with BCDs. Figure 3 shows the SRTs (in the Co-located and two Separated conditions) for the SSD (with and without BCDs) and NH groups as a function of age. Regression analyses revealed no significant correlation.