Listener ratings of speech benefit only become significant once SNR change reaches 4 dB

Evidence

Ratings increase near linearly as a function of ΔSNR, and are asymmetric: when the + ΔSNR interval preceded the reference, ratings were less than when the + ΔSNR interval followed the reference (e.g., when the second interval was the better SNR, ratings were greater than one increment at a ΔSNR of 4 dB, but when the second interval was the worse SNR, ratings were greater than one increment only when ΔSNR was 8 dB). This asymmetry was most likely due to an order effect; the second iteration of a sentence has been shown to be more intelligible (e.g., Thwing 1956 ), hence second-interval deficits would be deflated, and second-interval benefits inflated. Regarding the JMD, the ratings significantly increased only at 4 dB, regardless of order, lending support to the notion of detectability being a requisite for meaningfulness. — Dijk, Pim van, Physiology, Psychoacoustics and…, 5688

Categorization

Category: Factual Claims

• XREF: Connects to the JND/detectability findings in earlier sections of this volume — meaningfulness thresholds may track just-noticeable-difference detectability.

Related

• Meaningful hearing benefit emerges at 4 dB SNR regardless of presentation order (similarity 0.92)
• Listeners only rate a speech-quality change as meaningful when it exceeds detectability thresholds (similarity 0.91)
• Listeners value loudness increases as much as SNR improvements they provide (similarity 0.90)
• Detection threshold for SNR change in sentences averages about 3 dB (similarity 0.87)
• Detectability alone fails to capture what hearing benefit users deem meaningful (similarity 0.87)
• Listeners value a level change as much or more than an equal-dB SNR change (similarity 0.87)
• Listeners may judge SNR changes via perceived intelligibility rather than raw signal level (similarity 0.87)
• A repeated sentence is more intelligible on second hearing (similarity 0.86)
• Hearing benefit ratings are inflated for second-presented sentences due to an order effect (similarity 0.86)
• Meaningful speech-in-noise benefit requires double the detectable SNR change (similarity 0.86)
• SNR must rise at least 3 dB before listeners tolerate one more conversation (similarity 0.85)
• Hearing aid SNR improvements fall below the just-noticeable threshold for speech understanding (similarity 0.85)
• Listeners’ SNR JNDs may actually be intelligibility JNDs, not signal-level ones. (similarity 0.85)
• Hearing-aid benefit studies lack an agreed threshold for meaningful SNR improvement (similarity 0.84)
• The just noticeable difference in signal-to-noise ratio for speech is about 3 dB (similarity 0.84)