Comparison of Co-articulation Perception in Individuals with Normal Hearing and Hearing Impairment

Abstract

The aim of the study was to compare the ability of normal hearing listeners and those with hearing impairment to utilize coarticulation cues in the identification of the fricative /ƒ/. The participants included 19 listeners with normal hearing and 18 listeners with flat sensorineural hearing impairment. Among the 18 individuals with hearing impairment, 9 had mild hearing loss and 9 had moderate hearing loss. They were evaluated using the stimuli /aƒa/, /iƒi/ and /uƒu/ spoken by two talkers, one male and one female. Further, in the anticipatory condition the stimuli were truncated to include the preceding vowel with varying durations of the fricative noise (0%, 20%, 40%, 60%, & 80%). Similarly, in the carryover condition the stimuli were truncated to include the following vowel along with varying durations of the fricative noise (0%, 20%, 40%, 60%, 80%, & 100%). The participants were asked to write down the speech sounds heard by them from a given set of choices. The number of /ƒ/ responses heard by the participants at each truncation was analyzed. A Shapiro- Wilk test of normality was carried out. Since the data were not normally distributed, nonparametric statistical tests were carried out. A significant difference in performance was noted between individuals with normal hearing and those with moderate hearing impairment, and between listeners with mild and moderate hearing impairment. Also, significant differences were noted across adjacent truncations in each of the three participant groups. It was further noted that performance in anticipatory coarticulation was significantly better than carryover coarticulation. The study indicated that the overall ability to utilize coarticulatory cues reduced with increasing degrees of hearing loss. Also, in each of the groups, the performance in the anticipatory condition was better than the carryover condition.