A Comparative Study of Gap Detection Threshold in Cochlear Implant Users & Normal Hearing Children

Gap detection test is used as one measure of the temporal resolving power of the auditory system, i.e., the ability to follow rapid changes over time. The typical threshold for detection of a gap in a wideband noise burst is 2-3 ms (Green, 1985). A Cochlear Implant (CI) is a device that can be surgically implanted into a person’s cochlea to stimulate it to cause hearing. It is essential neural stimulator, which directly stimulate auditory nerve & interpreted as sound at the level of auditory cortex. Due to limited discrimination of frequency CI recipients has more difficulty in understanding speech sounds. A total of 10 normal hearing children & 20 children with cochlear implant in the age range of 7-20 years were included in the study. Gap Detection Thresholds were measured for 500Hz, 1K Hz, 2K Hz and 4K Hz frequencies in normal hearing individual and other four groups i.e. CI recipients with 2, 5, 10 and 15 months of postop duration. It was observed that there was significant difference between normal hearing and cochlear implant group individuals. Cochlear implant group’s gap detection thresholds were poor in comparison to normal hearing group individuals. Poor GDT is seen in CI because they rely on either temporal or spectral cues.