Voice onset time production and perception in apraxic subjects

Area of Science:

• Speech-language pathology
• Acoustic phonetics
• Neurolinguistics

Background:

• Apraxia of speech is a motor speech disorder affecting speech planning and programming.
• Voice onset time (VOT) is a crucial acoustic cue differentiating voiced and voiceless consonants.
• Understanding VOT perception and production in apraxia is vital for targeted interventions.

Purpose of the Study:

• To investigate the relationship between voice onset time (VOT) perception and production in individuals with apraxia of speech.
• To determine if production deficits in VOT correlate with perceptual difficulties in differentiating speech sounds.

Main Methods:

• Acoustic analysis of spectrograms for VOT measurement in words like 'bees' and 'peas' produced by apraxic subjects.
• Perceptual testing using synthetic speech stimuli to assess VOT discrimination across a voiced-to-voiceless continuum.
• Correlation analysis to examine the relationship between acoustic VOT measures and perceptual VOT judgments.

Main Results:

• Apraxic subjects demonstrated measurable errors in both the production and perception of voice onset time (VOT).
• Specifically, difficulties were observed in the voicing feature, impacting consonant distinction.
• No significant statistical relationship was identified between the acoustic measures of VOT production and the perceptual VOT identification accuracy.

Conclusions:

• Individuals with apraxia of speech exhibit deficits in both producing and perceiving the voicing feature, specifically related to VOT.
• Despite co-occurring production and perceptual errors, these deficits appear independent in apraxic speakers.
• Further research is needed to elucidate the underlying mechanisms and inform treatment strategies for VOT-related challenges in apraxia.