Weighting of acoustic cues shifts to frication duration in identification of fricatives/affricates when auditory properties are degraded due to aging

In previous studies, we conducted several experiments, including identification tests for young and elderly listeners using /shi/–/chi/ (CV) and /ishi/–/ichi/ (VCV) continua. For the CV stimuli, confusion of /shi/ as /chi/ increased when the frication had a long rise time, and /chi/ was confused with /shi/ when the frication had a short rise time. This was true for the group with the following auditory property degradation: 1) elevation of absolute threshold, 2) presence of loudness recruitment, and 3) deficit of auditory temporal resolution. When auditory property degradation was observed, the weighting of acoustic cues shifted to frication duration rather than the gradient of the amplitude of frication. The latter was calculated by dividing frication amplitude by rise time. In the VCV stimuli, confusion of /ichi/ as /ishi/ occurred for a long silent interval between the first V and C with auditory property degradation, and the weighting of acoustic cues shifted from the silent interval to frication duration. In the present study, we unified these findings into a single framework and found that degradation of auditory properties causes listeners to prefer duration of frication as a cue for identifying fricatives and affricates.