Speech-in-noise measures: variable versus fixed speech and noise levels.

OBJECTIVE The purpose was to determine if speech-recognition performances were the same when the speech level was fixed and the noise level varied as when the noise level was fixed and the speech level varied. DESIGN A descriptive/quasi-experimental experiment was conducted with Lists 3 and 4 of the revised speech perception in noise (R-SPIN) test, which involves high predictability (HP) and low predictability (LP) words. The R-SPIN was modified into a multiple signal-to-noise paradigm (23- to -1-dB in 3-dB decrements) from which the 50% points were calculated with the Spearman-Kärber equation. STUDY SAMPLE Sixteen young listeners with normal hearing and 48 older listeners with pure-tone hearing losses participated. RESULTS The listeners with normal hearing performed better than the listeners with hearing loss on both the HP and LP conditions. For both groups of listeners, (1) performance on the HP sentences was better than on the LP sentences, and (2) the mean 50% points were 0.1 to 0.4 dB lower (better) on the speech-variable, babble-fixed condition than on the speech-fixed, babble-variable condition. CONCLUSIONS For practical purposes the ≤ 0.4-dB differences are not considered noteworthy as the differences are smaller than the decibel value of one word on the test (0.6 dB).