Individual differences in the acquisition of the /t/-/k/ contrast: A study of adults' perception of children's speech

Abstract

The presence of subtle but meaningful within-category sound differences has been documented in acoustic and articulatory analyses of children's speech. This study explored visual analog scaling (VAS) to measure speech perception. Productions of word-initial /t/ and /k/ were recorded from a diverse group of 63 children aged 28 to 39 months. Adult na�ve listeners rated productions on a VAS. Measures of children's vocabulary, speech perception, executive function, home language environment, and maternal education level were collected. Robustness of the /t/-/k/ contrast was derived from adult VAS ratings for each talker. Speech accuracy, based on phonetic transcriptions was calculated. Listeners differentiated transcription categories, including intermediate categories, using the VAS. Listeners had variable levels of intra-rater reliability, and set effects were present. Transcription accuracy and robustness of contrast were closely related, but robustness of contrast highlighted differences between children with high accuracy. Vocabulary measures predicted both robustness of contrast and transcribed accuracy.