Speech perception in children with cochlear implants for continua varying in formant transition duration

To examine the developmental course of labial and alveolar manner of articulation contrasts, and to determine how that course may be different for typically developing (TD) children with cochlear implants (CI).

Eight young adults, eight TD 5-8 year-old children, and seven 5-8 year-old children with CIs participated. Labial /ba/-/wa/ and alveolar /da/-/ja/ continua stimuli were presented, with each continuum consisting of nine synthetic stimuli varying in F2 and F3 transition duration. Participants were asked to label the stimuli as either a stop or glide, and responses were analysed for phonetic boundaries and slopes.

For the /ba/-/wa/ contrast, children with CIs required longer transition durations compared to TD children or adults to cross from one phoneme category to another. The children with CIs demonstrated less confidence in labelling the stimuli (i.e. less steep slopes) than the TD children or the adults. For the /da/-/ja/ contrast, the children with CIs showed less steep slope values than adults.

These results suggest that there are differences in the way TD children and children with CIs develop and maintain phonetic categories, perhaps differences in phonetic representation or in linking acoustic and phonetic representations.