A Comparison of Two Approaches to Assessment of Speech Recognition Ability in Single Cases

Single-case design with the randomization test (RT) has been proposed as an alternative to the binomial distribution (BD) tables of Thornton and Raffin (1978) to assess changes in speech recognition performance in individual subjects. The present study investigated whether data analyzed using both approaches would result in similar outcomes. Sixty-two adults with normal hearing were evaluated using phoneme scoring and a restricted alternating treatments design under two signal-to-noise conditions. Results revealed a significant correlation between the RT and a BD analysis using at least 50-word lists, although the BD analysis was a more sensitive measure. The absence of correlation between the RT with a BD analysis using 25-word lists challenges the common clinical practice of using reduced list size, and supports the use of phoneme scoring and other attempts to find clinically acceptable yet evidence-based solutions to overcome the conflict between time and accuracy.

Key Words

Binomial model - phoneme scoring - randomization test single case design - speech recognition tests