Temporal and Spectral Cues for Phoneme Perception in School-Age Children and Adults

Purpose: This study considered the impact of spectral and temporal smearing on vowel and consonant discrimination in school-age children and adults with normal hearing (NH). The overall purpose of this work was to test the hypothesis that degraded spectral cues preferentially impact vowel discrimination, while reduced access to temporal cues preferentially affects consonant discrimination. This work is a first step toward understanding how the effects of poor spectral and temporal resolution may affect phonological awareness and speech perception in children with cochlear hearing loss (C-HL) and auditory neuropathy (AN). Method: Participants were 10 young adults and 18 school-age children with NH. Speech perception testing included vowel and consonant minimal pair discrimination for stimuli that were either unprocessed, spectrally smeared, or temporally smeared. All participants completed psychophysical estimates of spectral, temporal, and intensity resolution as well as standardized assessments of phonological awareness and receptive vocabulary. Results: Psychophysical estimates of spectral, temporal, and intensity resolution for unprocessed stimuli were consistent with previous literature, including improvement in thresholds as a function of child age. As predicted for both age groups, spectral smearing had greater effects on vowel discrimination, while temporal smearing had greater effects on consonant discrimination with minimal pairs differentiated by either presence/absence of a stop consonant or voicing. All participants demonstrated normal, age-adjusted, phonological awareness, and receptive vocabulary skills. Conclusions: For both children and adults, degraded spectral and temporal cues differentially affected access to vowel and consonant information. These results suggest the need for further investigations evaluating the effects of long-term reductions in access to spectral and temporal cues in children with hearing loss. This topic is particularly relevant to hearing losses such as C-HL and AN, which are primarily characterized by reduced perception of spectral and temporal acoustic cues, respectively. Supplemental Material: https://doi.org/10.23641/asha.29660819