Phonetic difficulty and stuttering in English.

Area of Science:

• Speech and Language Pathology
• Linguistics
• Developmental Psychology

Background:

• Previous research indicates phonetic difficulty disproportionately affects older stuttering speakers, especially on content words.
• Older speakers who stutter show greater difficulty with content words compared to function words.

Purpose of the Study:

• To examine the relationship between stuttering rate and the Index of Phonetic Complexity (IPC) in different age groups.
• To validate the IPC as a measure of phonetic difficulty in stuttering.
• To identify and rank the factors contributing to stuttering in English.

Main Methods:

• The study analyzed stuttering rate against the IPC score across function and content words in three age groups (6-11, 11-18, 18+).
• Phonetic complexity was assessed using the IPC, a recently developed index.
• Further analyses identified and ordered factors influencing stuttering in English.

Main Results:

• The hypothesis that stuttering rate on content words correlates with IPC scores in older speakers was supported.
• The IPC's validity was supported by its similarity to previous analyses of phonetic features.
• The order of importance for factors leading to stuttering was identified as: consonant manner, consonant place, word length, and consonant clusters.

Conclusions:

• Phonetic difficulty, measured by IPC, significantly relates to stuttering in older individuals.
• The findings suggest some factors influencing stuttering may be acquired rather than innate, warranting cross-linguistic research.
• Early childhood disfluency on function words appears influenced by factors beyond phonetic complexity.