Characteristics of Lexical Stress in Hebrew-Speaking Children With Childhood Apraxia of Speech

The purpose of the present study was to explore the ability of Hebrew-speaking children with childhood apraxia of speech (CAS) to produce lexical stress.

A total of 36 children aged between 4 and 7 years, 18 children with CAS, and 18 typically developing (TD) children participated in the study. All children completed language and speech assessments. The children imitated 20 weak-strong and strong-weak target words within short sentences and in isolation. Acoustic analysis of the vowels in the stressed and unstressed syllables of the target words and perceptual judgment of the words by six speech-language pathologists were conducted.

The acoustic analysis showed significant differences in duration, fundamental frequency, and amplitude between stressed and unstressed vowels in weak-strong and strong-weak words and in both groups of children. The total duration for both the stressed and weak syllables was longer in children with CAS compared to TD children. Rated on a Likert scale of 1-5, where 5 indicates correct production, the productions of lexical stress in the CAS group were judged as above 4 on average but were significantly worse compared to the TD group. The target productions of children with CAS were judged as including excessive, equal, or misplaced stress in 10.8% of the productions, whereas 5.8% of the target productions of the TD children were judged as having inappropriate stress.

The present findings suggest that Hebrew-speaking children with CAS produce the acoustic characteristics of lexical stress similarly to their peers, and their productions are perceived as having relatively good lexical stress (above 4), although not as good as TD children.