Speech intelligibility saturates beyond certain signal-to-noise ratio bounds.

Evidence

Speech intelligibility in noise is strongly influenced by the relative level of the target compared to that of the noise, referred to as signal-to-noise ratio (SNR). High SNRs lead to better speech recognition than low SNRs. But, although SNRs can take infinite values, it is not the case for speech intelligibility. Some SNR floors and ceilings must exist, such that intelligibility would not be influenced by varying the SNR above or below these limits. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3538

The most important parameter that affects the ability to hear and understand speech in the presence of background noise is the signal-to-noise ratio (SNR). Despite decades of research in speech intelligibility, it is not currently known how much improvement in SNR is needed to provide a meaningful benefit to someone. We propose that the underlying psychophysical basis to a meaningful benefit should be the just noticeable difference (JND) for SNR. — Dijk, Pim van, Physiology, Psychoacoustics and…, 5667

Categorization

• DEFINE: Introduces SNR and the floor/ceiling concept central to the chapter.
• corroborated: 3 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 3538; Dijk, Pim van, Physiology, Psychoacoustics and…, 5667
• XREF: connects to: Improving speech intelligibility via noise reduction outweighs equivalent improvement of the target signal. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3536; Speech intelligibility saturates once the low-frequency target is attenuated 15 dB.; The range of SNRs contributing to speech intelligibility is wider than SII standards assume (+4 more)

Broader Connections

• Speech intelligibility saturates once the low-frequency target is attenuated 15 dB. #qualifies (0.85)
• Speech reception thresholds plateau beyond a target low-pass attenuation floor #corroborates (0.85)
• Every 1 dB of signal-to-noise improvement raises speech intelligibility by 7 to 19 percent #contradicts (0.82)
• Speech intelligibility models need nonlinear SNR-importance functions for filtered sources #expands (0.78)
• The range of SNRs contributing to speech intelligibility is wider than SII standards assume #qualifies (0.75)