Normal-hearing listeners detect a 3 dB change in speech-to-noise ratio

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 SNR JNDs at the three SNR references of ‑6, 0 and + 6 dB SNR were 2.8, 2.9, and 3.7 dB respectively; the first two were statistically no different and both less than the third [t (91. — Dijk, Pim van, Physiology, Psychoacoustics and…, 5674

Categorization

• XREF: Connects to the classic Weber-fraction finding that JND scales roughly proportionally with stimulus level, here extended to SNR discrimination, and to the reader’s broader interest in psychoacoustic thresholds in normal hearing.