Variability and sequential order of consonant normalization in children with speech delay

Area of Science:

• Linguistics
• Developmental Psychology
• Speech-Language Pathology

Background:

• Establishing a definitive rank order for English consonant development is challenging due to individual variability and theoretical discrepancies.
• Previous models, like Jakobson's, offer insights but don't fully account for observed acquisition patterns.
• Speech delay (SD) presents unique challenges in understanding typical developmental trajectories.

Purpose of the Study:

• To establish a reliable rank order of English consonant acquisition in children with speech delay.
• To investigate the utility of survival analytic techniques in developmental speech research.
• To test the validity of the strong delay hypothesis by comparing derived probabilities with normative data.

Main Methods:

• Utilized Kaplan-Meier (KM) survival analysis on conversational speech data from 24 children with speech delay over two years.
• Determined rank order of acquisition for consonants with probabilities exceeding .75.
• Applied the strong delay hypothesis to lag normalization probabilities for comparison with existing normative studies.

Main Results:

• A rank order of consonant acquisition was established, showing alignment with place and manner of articulation, partially mirroring Jakobson's predictions.
• Lagging the derived probabilities according to the strong delay hypothesis led to convergence with established normative data (Prather et al., 1975; Sander, 1972).
• The findings indicate that survival analysis can effectively model consonant acquisition patterns.

Conclusions:

• Survival analytic techniques, specifically KM analysis, provide a robust method for ranking consonant acquisition, accommodating individual variability.
• The convergence of results supports the generalizability of the findings and provides evidence for the strong delay hypothesis in speech development.
• This approach offers a more nuanced understanding of consonant acquisition in children with speech delay.