SNR discriminations can be measured with a two-interval forced-choice clarity task

Evidence

The JND for SNR was measured for adults of varying hearing ability at different reference SNRs using adaptive and fixed-level procedures based on the classic level discrimination paradigm (cf. McShefferty et al. 2015 ). The stimuli were equalised IEEE sentences uttered by a native British English speaker (Smith and Faulkner 2006 ) in same-spectrum noise, presented over headphones in a sound-attenuated booth. Noises began and ended simultaneous with the speech signal, and there was a 500-ms gap between intervals. Both intervals contained the same randomly chosen sentence, and after both intervals, participants were prompted to respond to which one was clearer. In each interval the levels of both speech and noise were adjusted to maintain a presentation level of 75 dB A; to minimize other cues, the level of each interval was roved independently by a maximum of ±2 dB. In a two-interval/alternative forced-choice task, participants were presented, in randomized order, with a reference interval at a fixed reference SNR (either ‑6, 0, or + 6 dB), and a target interval at the reference SNR plus an increment (ΔSNR) that was either varied adaptively or presented at fixed, randomly interleaved ΔSNRs. The adaptive procedure estimated 79 % correct from the geometric means of the best two of three three-up/one-down tracks. The fixed-level procedure estimated 79 % correct from fitting a maximum-log-likelihood logistic function to the data. The procedures produced equivalent results to 0.1 dB, so results were combined across procedures for each reference SNR. — Dijk, Pim van, Physiology, Psychoacoustics and…, 5675

Categorization

• SHARE: A hearing-science colleague would appreciate the detail that adaptive and fixed-level procedures agree to 0.1 dB, confirming robustness across estimation methods.