RESUMO
Temporal processing is critical to a wide variety of everyday listening tasks, including speech perception. Although the importance of signal to noise ratio (SNR) is well documented in speech perception experiments, it is less explored in temporal processing experiments. The present study examined the effect of SNR on temporal processing abilities using Gap Detection Threshold (GDT) in children and adults. The study included a total of 45 subjects, where in, 25 children (Group-1) and 20 adults (Group-2) with pure-tone thresholds ranging from 0 to 25 dB HL at frequency range 250-8000 Hz. The GDT was measured at presentation level 50 dBSL. All the measurements were performed in 5 different conditions: 'Quiet', ' + 10 dB SNR', ' + 5 dB SNR', ' + 0 dB SNR' and ' - 5 dB SNR'. Gap Detection Thresholds are significantly higher from + 10 to - 5 dB SNR when compared to quiet condition in young-adults and all sub-groups of children, whereas at + 10 dB SNR, thresholds were not significantly different from quiet condition in young-adults and all sub-groups of children except for sub-group A of children, and were significantly different for all the five conditions. It was revealed that, as the signal to noise ratio (SNR) was decreased from + 10 dB SNR to 0 dB SNR there was a significant increase in Gap Detection Thresholds. There was a significant increase in Gap Detection Thresholds from + 10 dB SNR to - 5 dB SNR in both children and adults. The results also suggest that the performance on temporal processing task in the presence of background noise achieves young-adult like pattern by the age of 10-11 years. Background noise affect temporal processing in both children and young-adults. Background noise impairs temporal processing in children more than the adults, which could be because of poor temporal resolving abilities in children.
RESUMO
The advent of Cochlear Implants (CI) has bought with it, the goal of spoken language performance for severe-profound sensori-neural hearing loss (SNHL) as par with the normal hearing listeners. The aim of this study was to evaluate the outcome of paediatric cochlear implantation in auditory and speech skills below the age of 5 years. The present study consisted of 50 childrens. Auditory skills were assessed in terms of audiometric thresholds and localization abilities. Speech - Language skills were measured using; Categories of Auditory Performance -CAP; Meaningful Use of Speech Scale - MUSS; Meaningful Auditory Integration Scale - MAIS and Speech intelligibility Rating - SIR. Hearing thresholds obtained from all the subjects for pre implant and post implant conditions of 3rd, 6th, 9th, 12th month conditions, evidenced a high significant (p < 0.001) improvement across all test frequencies 500, 1000, 2000 and 4000 Hz. There was also a statistically significant difference across successive measurements of auditory and speech skills, as determined by ANOVA (F (4, 245) = 151.33, p < 0.001 for CAP; F (4, 245) = 89.636, p < 0.001 for SIR; F (4, 245) = 812.282 p < 0.001 for MAIS and F(4, 245) = 435.677 p < 0.001 for MUSS). Auditory localization abilities were also improved considerably over a period of one year. The present study added the evidence to the literature that cochlear implants significantly improved the hearing ability of children with severe-to-profound hearing loss. This study also demonstrated that, children were better able to make use of the auditory information perceived through the implant.
