Every 1 dB of signal-to-noise improvement raises speech intelligibility by 7 to 19 percent

Evidence

The direct sound: This is the sound that carries information and articulation. For speech it is important that the listener receive a large amount of direct sound if they are to comprehend the words easily. Unfortunately, as discussed in Chapter 1, the direct sound gets weaker as it spreads out from the source. Every time you double your distance from a sound source the level of the direct sound goes down by a factor of four, that is, an inverse square law. Thus the further away you are from a sound source, the weaker the direct sound component. — David Howard, Jamie Angus, coustics and Psychoacoustics, 2434 (#expands, via linked claim)

Categorization

• XREF: connects to: Directive microphone arrays in hearing aids improve speech intelligibility in noise; Speech intelligibility saturates beyond certain signal-to-noise ratio bounds. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3538; Speech intelligibility gains more from reducing masker energy than from increasing target energy (+7 more)

Broader Connections

• Speech intelligibility depends on high direct-to-reverberant sound ratios #expands (0.75) — David Howard, Jamie Angus, coustics and Psychoacoustics, 2434