Vowel patterns in developmental apraxia of speech: three longitudinal case studies

Area of Science:

• Speech-Language Pathology
• Linguistics
• Developmental Pediatrics

Background:

• Developmental apraxia of speech (DAS) is a complex speech disorder affecting motor planning.
• Vowel production is crucial for intelligibility, yet often overlooked in DAS research.
• Longitudinal data on vowel accuracy in DAS is limited.

Purpose of the Study:

• To analyze vowel inventories and error patterns in children with suspected DAS over three years.
• To investigate the relationship between vowel accuracy, utterance length, and syllable complexity.
• To determine if vowel production can serve as a clinical marker for DAS diagnosis.

Main Methods:

• Phonetic transcriptions of connected speech samples from three children with suspected DAS.
• Analysis of vowel inventories and accuracy over a 3-year period.
• Examination of error patterns in relation to utterance length and syllable complexity.

Main Results:

• Children exhibited complete English vowel inventories, excluding rhotics.
• Vowel accuracy in connected speech did not normalize over the study period.
• No consistent vowel error patterns were identified, and accuracy was not affected by utterance length or complexity.

Conclusions:

• Vowel inaccuracy can persist in children with DAS despite a complete vowel inventory.
• Longitudinal data on vowel production is valuable for understanding DAS.
• Vowel accuracy warrants further investigation as a potential clinical marker for differential diagnosis of DAS.