The Effect of the Slope of the Psychometric Function on the Measurement of Speech Recognition Threshold Using a Male Talker

• Main Author: Bakhsh, Nujod Ali
• Format: Others
• Published: BYU ScholarsArchive 2018
• Subjects: slope of the psychometric function; speech recognition threshold; speech audiometry; Communication Sciences and Disorders
• Online Access: https://scholarsarchive.byu.edu/etd/6841; https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=7841&context=etd

Speech audiometry is the aspect of audiology that provides critical information on how individuals hear one of the most important sounds of daily life: speech. The speech recognition threshold (SRT) is a measure of speech audiometry that is widely used to provide information on an individual's capacity to hear speech. Over time, researchers and clinicians have worked to improve the SRT by developing and modifying a variety of word lists to be used during testing. Eventually, spondaic words were selected as the best stimuli for the SRT. The spondaic words had to meet four criteria: familiarity, phonetic dissimilarity, normal sampling of English sounds, and homogeneity with respect to audibility. This study examined the aspect of homogeneity with regard to slope of the psychometric function. Specifically, whether slope of the psychometric function had an effect on the number of words used to obtain the SRT, and thus reduce test time, as well as whether slope had an effect on the relationship between the SRT and the pure-tone average (PTA). It was hypothesized that words with a steep slope would significantly reduce test time and yield a close SRT-PTA agreement. Three word lists (steep, medium, and shallow sloping words), all recorded by a male talker, were used to obtain the SRT on 40 participants (ages 18-30 years). Statistical analysis showed significant differences in the number of words to obtain the SRT and the SRT-PTA agreement. However, when the differences were examined from a clinical perspective, the results were negligible. When compared with words with medium and steep slopes, words with shallow slope required an average of four extra words to obtain the SRT, which does not result in a meaningful reduction in test time. For clinical purposes, it appears that the slope of the psychometric function does not need to be taken into consideration for the SRT. Clinicians may use a variety of words as long as they meet the original four criteria for selection of spondees.