Speech Perception in Children with Cochlear Implants for Continua Varying in Formant Transition Duration

Abstract

The purpose of the study was to examine the developmental effects of duration cues by comparing the phonetic boundaries and slopes of typically-developing (TD) children to adults on a stop-glide continuum, to examine the effects of duration cues in children with cochlear implants (CIs) on a stop-glide contrast (i.e., [ba] –[wa] and [da]-[ja]) as they relate to the auditory temporal deficit hypothesis (Tallal, 2000) and, to explore the impact of auditory sensitivity (i.e., hearing loss versus normal hearing) by comparing the slopes and phonetic boundaries of children with CIs to TD children on a stop-glide continuum. Three groups of participants participated in the study: eight adults, eight five- to eight-year-old TD children, and seven five- to eight-year-old children with CIs. The participants were presented with two nine-step stop-glide continua (i.e., [ba] –[wa] and [da]-[ja]) with each step presented ten times for a total of 180 stimuli. The presentations of the stimuli were blocked for place of articulation and were randomly presented within each continuum. The results of the study revealed developmental effects in the perception of duration cues between the adults and TD children. The performance of children with CIs did not support the prediction of auditory temporal processing deficit in that there were no differences in the ability to label the endpoints of the continua. The auditory temporal deficit predicted that the children would have improved performance at the glide end compared to the stop end of the continua. However, the children with CIs have phonetic boundaries that are significantly shifted to the glide end of the continuum compared to the TD children. This finding suggests that children with CIs require longer duration cues to make the phonetic shift compared to TD children, which supports the auditory sensitivity hypothesis. The children with CIs had significantly shallower slopes and shifted phonetic boundaries compared to the TD children. This suggests that degraded auditory sensitivity such as hearing loss adversely impacts speech perception on a stop-glide continuum.