Not all /r/s and /l/s are the same: Classification of errors in children with cochlear implants versus normal hearing

Abstract

Purpose: As children acquire speech sounds, they progress from clear substitutions, to “intermediate forms” (covert contrasts), to adult-like productions. However, there is evidence that this progression may be different in CI users as compared to NH children. Identification of intermediate forms is dependent upon rating scales that are sensitive to fine phonetic detail, such as visual analogue scales (VAS). This study uses both traditional VAS and a new 3-dimensional rating scale to explore differences in the /r,l/ productions of young children with and without hearing loss. Methods: Correct and error productions of /r,l/ were extracted from a standardized articulation test for nine congenitally deafened children who received cochlear implants (CIs) prior to age 3 and their speech age-matched controls. Stimuli were shortened to nonsense syllables to prevent real-word bias. Listeners rated these productions on both a VAS and a triangular scale, which allowed listeners to rate phone quality as a multi-dimensional function of /r/, /l/, and /w/. Results & Conclusions: Both rating scales were sensitive to subtle acoustic differences in speech sounds. Listener responses suggested more variability in sound production within the group of CI users. Listeners preferred the triangular scale because it provided greater response sensitivity.