Evaluation of delayed auditory feedback (DAF) effect: comparison between subjective judgments and objective measures.

Area of Science:

• Neuroscience
• Speech-Language Pathology
• Psycholinguistics

Background:

• Delayed Auditory Feedback (DAF) is known to affect speech production.
• Understanding its impact on speech duration is crucial for therapeutic interventions.
• Aphasia, a language disorder resulting from brain damage, often affects speech fluency and duration.

Purpose of the Study:

• To evaluate the effects of DAF on speech duration.
• To compare subjective and objective measurement methods for DAF effects.
• To assess DAF's impact across different participant groups: normal speakers, nonfluent aphasics, and fluent aphasics.

Main Methods:

• Thirty subjects (10 normal, 10 nonfluent aphasic, 10 fluent aphasic) participated.
• Speech duration was assessed under DAF conditions (180 msec and 360 msec delays).
• Both subjective listener ratings and objective acoustic measurements were employed.

Main Results:

• A moderate to strong correlation (r = .52 for 180 msec, r = .46 for 360 msec) was found between subjective and objective data.
• Analysis of variance revealed significant differences among groups, delay conditions, and tasks for both measurement methods.
• Both methods demonstrated comparable sensitivity in detecting DAF effects.

Conclusions:

• Subjective and objective procedures are equally effective for evaluating DAF's impact on speech duration.
• These methodologies can be valuable tools for assessing DAF effects and potentially other behavioral changes.
• The findings support the use of both assessment types in clinical and research settings for speech disorders.