Recording and Evaluation of an American Dialect Version of the Four Alternative Auditory Feature Test

Abstract

Background: The Four Alternative Auditory Feature test (FAAF) is a word-based closed-set speech recognition test. Because the original test materials were recorded in British English dialect, it is not appropriate for use in the United States. Purpose: The purpose of this study was to produce an American dialect FAAF (AFAAF). Research Design: The AFAAF materials spoken by a native American-English speaking male were recorded and digitally edited. In the validation study, the AFAAF was administered monaurally at five signal-to-noise ratios (SNRs) in both ears for each listener. Study Sample: A total of 20 young adults with normal hearing participated in the validation study. Data Collection and Analysis: For each participant, speech recognition scores were collected in one session. The speech level was fixed at 70 dB SPL and the steady-state talker-matched noise level was varied, resulting in five SNRs from –15 to –5 dB. One full list (80 words) was used for each SNR. For each participant, a performance-intensity (PI) function was fit to the discrete mean percent correct scores for the five SNRs according to a best-fit, three-parameter sigmoid function. In addition, scores for the left and right ears were compared to examine test-retest reliability. Results: Results show that the slope of the PI function is 6% per dB, the mean test-retest difference scores for the five SNRs are within 3 rationalized arcsine units (rau), and the 95% critical difference for the 80-word scores is 12 rau. Compared with the FAAF, the slope of the PI function for the AFAAF is slightly less steep. Test-retest reliability of the AFAAF is at least equal to that of the FAAF. Conclusions: It is concluded that the AFAAF is similar but not identical to the FAAF. The AFAAF is now available for measuring speech recognition performance in listeners who use American English as a native language.