Acoustic analysis of vowel production in children with childhood apraxia of speech

Abstract

Childhood apraxia of speech (CAS) is a complex neurological subtype of speech sound disorder (SSD), involving impaired speech motor planning and programming. Speech characteristics of CAS include difficulty in sequencing speech movements in the absence of muscle weakness resulting in segmental (e.g., vowel/consonant distortions) and suprasegmental (e.g., inappropriate lexical stress) speech deficits. Acoustic analysis offers a robust objective diagnostic measurement of CAS for lexical stress and consonant accuracy/consistency. However, other reported CAS features, such as vowel errors and distortions, have yet to be extensively validated using acoustic analyses. This study will acoustically analyze vowel errors and inconsistencies for corner vowels (/i, u, æ, ɑ/) in children with CAS (aged 8;0 to 15;11) compared to peers with SSD and typical development (TD). Vowel space measures (e.g., vowel space area and formant centralization ratio) and consistency (e.g., vowel cluster distribution) will be assessed in 24 children (CAS = 4, SSD = 10, and TD = 10) across various phonetic contexts (e.g., syllable sequencing between anterior to posterior voiced/voiceless stops of increasing syllable length). It is predicted that children with CAS will demonstrate (1) greater vowel inconsistencies as context complexity increases and (2) a neutralized vowel space based on the corner vowels relative to children with SSD and TD.