Measured SNR JNDs may actually reflect intelligibility rather than SNR discrimination
Evidence
This raises the question as to whether the JNDs initially measured (in Sect. 2.1 above) were intelligibility rather than SNR JNDs (i.e., were the listeners basing their responses on changes in word intelligibility or in changes in signal-to-noise ratio?) We reasoned that by changing the stimuli to ones with a far steeper psychometric function (MacPherson and Akeroyd 2014 ), namely triple digits, the JND in the appropriate domain would be constant, but the JND in the other domain would change. On testing this hypothesis, we found that the mean SNR JND for digits was 2.5 dB (σ= 0.8 dB) and the mean Intelligibility JND estimate for digits was 17.5 % (σ= 7.2 %). SNR and Intelligibility JNDs were significantly less using digits in unfiltered random (white) noise than sentences in same-spectrum noise [t (23) = 2.98; p = 0.007 and t (23) = 5.00; p = 0.00005]. Across stimuli, both the SNR JND differences (mean 0.5 dB) and the Intelligibility JND differences (mean 8.92 dB) were significantly non-zero (z(23) = 2.98; p = 0.003, and z(23) = 5.00; p ≈ 0). That both differences were non-zero was unexpected; it indicates that one cannot be certain whether the 3 dB SNR JND is indeed the JND for SNR or instead the JND for Intelligibility. — Dijk, Pim van, Physiology, Psychoacoustics and…, 5683
Categorization
- QUESTION: An unresolved interpretive ambiguity in JND measurement that could be followed up in the methodology literature.
- corroborated: 2 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 5683
- XREF: connects to: Listeners may judge SNR changes via perceived intelligibility rather than raw signal level — Dijk, Pim van, Physiology, Psychoacoustics and…, 5669; Listeners’ SNR JNDs may actually be intelligibility JNDs, not signal-level ones.; A 3 dB SNR just-noticeable difference corresponds to a 26% intelligibility change in listeners. — Dijk, Pim van, Physiology, Psychoacoustics and…, 5669
Broader Connections
- Listeners’ SNR JNDs may actually be intelligibility JNDs, not signal-level ones.
#corroborates(0.98)