Abstract:
Aim and Objectives: The present study aimed to measure the spectral resolution using the Spectro-temporal Ripple Test with Narrowband Noise Carrier (STRt-NBN test) with Equivalent Rectangular Bandwidth (ERB) and Logarithmically-spaced ripples in individuals with normal hearing and cochlear hearing loss. The thresholds were compared across the two for the subjects with normal hearing and cochlear hearing loss. The psychophysical tuning curves, which are considered a standard test for assessing spectral resolution, were measured, each at 500, 1000, 2000, and 4000 Hz center frequencies. Psychoacoustic Tuning Curves (PTCs) were correlated with spectral resolution thresholds obtained for STRt-NBN-ERB spaced and STRt-NBN-Log spaced ripple perception tests.
Methods: Two groups of adults were considered in the study. Group I consisted of individuals with normal hearing and Group II consisted of individuals with cochlear hearing loss. All the participants had undergone testing with STRt-NBN with ERB spaced ripples and Log spaced ripples and PTCs (500Hz, 1000Hz, 2000Hz and 4000Hz).
Results and Discussion: The STRt-NBN with ERB spaced ripple thresholds were significantly better than STRt-NBN with Log spaced ripple thresholds, for individuals with normal hearing and those with hearing loss. Between group comparison revealed that individuals with hearing loss had poorer SRT-NBN thresholds and broader PTCs compared to the normal hearing. This suggests that the cochlear hearing loss group had poorer spectral resolution. Correlation of STRt-NBN-ERB spaced and STRt-NBN-Log spaced stimuli with PTCs revealed that the STRt-NBN with ERB-spaced ripple thresholds were significantly correlated with PTCs of 1000, 2000 and 4000 Hz. Conversely, correlation was found with PTCs and STRt-NBN with LOG-spaced ripples only at 4000Hz. The results suggested that ERB-spaced ripple stimuli can closely predict the spectral resolution than the Log-spaced ripple.
Conclusion: The STRt-NBN test with ERB spaced ripples better represents the spectral resolution of the cochlea in individuals with normal hearing and hearing loss. It can be used as a potential test to assess the spectral resolution abilities.
