Reliability, Sensitivity and Validity of Magnitude Estimation, Category Scaling and Paired-Comparison Judgments of Speech Intelligibility by Older Listeners: Fiabilité, sensibilité et validité du jugement de l'intelligibilité de la parole obtenues par estimation de la grandeur, estimation catégorielle et comparaison par paires chez des sujets aˇgés

Abstract

This study investigated the reliability, sensitivity, and validity of speech intelligibility judgments for hearing aid evaluation. Subjects aged 60–87 years judged the intelligibility of sentences using either magnitude estimation, category scaling or paired comparisons. The 60+ age group was chosen as representative of the majority of hearing aid wearers. Speech recognition scores for Central Institute for the Deaf (CID) sentences and Northwestern University Auditory Test No. 6 (NU-6) words were also obtained. The speech was bandpass filtered using filter settings that produce a monotonic increase in predicted intelligibility based on articulation index theory. Speech recognition scores and intelligibility judgments were obtained for each of eight filter conditions. Test-retest reliability was poorest for paired comparisons and CID sentence scores. There were no differences in sensitivity among the three psychophysical procedures. Intelligibility judgments and NU-6 scores were more sensitive than CID sentence scores to differences among conditions. The results indicated that intelligibility judgments are valid measures of speech recognition.

Key Words:

• Speech intelligibility
• Psychophysical scaling
• Magnitude estimation
• Paired comparisons
• Category scaling
• Hearing aids
• Rating scale