Normative data in quiet, broadband noise, and competing message for Northwestern University Auditory Test No. 6 by a...

Two descriptive experiments were performed on a version of the Northwestern University Auditory Test No. 6 (NU No. 6) recorded by a female speaker that is included on an audio compact disc recently produced by the Department of Veterans Affairs. In Experiment 1, normative psychometric functions for the female speaker version of the NU No. 6 materials were established on 24 young adults for three monaural listening conditions (in quiet, in 60-dB SPL broadband noise, and in 60-dB SPL competing message). The 60-dB SPL broadband noise shifted the psychometric function for the NU No. 6 words 33 dB, whereas the 60-dB SPL competing message shifted the function only 18-22 dB. In contrast to the slopes of the quiet and noise conditions (4.5%/dB), the slope of the competing message function was more gradual (3.5%/dB). In Experiment 2, comparisons between the psychometric functions for the female and the original male speaker versions of NU No. 6 in quiet and in broadband noise were made on 8 young adults. In comparison to the psychometric functions for the male speaker version of NU No. 6, the functions for the female speaker version of NU No. 6 were displaced between the 10-90% correct points to higher sound-pressure levels by 10-13 dB in quiet and by 12-16 dB in noise. The difference in performance on the two versions of NU No. 6 is attributed to spectral differences between the two sets of materials that produced a calibration anomaly.