Psychometric Function Characteristics of Time- Compressed Persian Words

Abstract

Background and Aim: The psychometric function characteristics (e.g. threshold and slope) of the time-compressed words have not been investigated in previous studies to compile psychometrically homogeneous word lists. Therefore, this study aimed to investigate psychometric function characteristics of monosyllabic time-compressed Persian words to develop psychometrically equivalent time-compressed word lists. Methods: Two hundred most common monosyllabic words in Persian language were time- compressed at a rate of 40%-85% and presented to 21 participants with normal hearing at a fixed intensity level. The threshold and slope of the psychometric function for all words were determined using the logistic regression. The compression ratio (CR) for 5%-95% correct recognition was predicted based on the psychometric function fitted to the measured correct recognition score. Results: Mean CR 50% of the words was in a range of 53%-78%. The mean CR 50% and slope were not significantly different between consonant-vowel-consonant and consonant- vowel-consonant-consonant words. The predicted CR for 5%-95% correct recognition varied from 61.5% to 88.4%. The final result was two 50-word lists of monosyllabic words with the same mean threshold and slope. Conclusion: Persian time-compressed monosyllabic words have different CR 50% and slope that may interact with their intelligibility. Keywords: Time compression; intelligibility; psychometric function; Persian monosyllabic words