Speech intelligibility depends on high direct-to-reverberant sound ratios
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
Sound reinforcement of speech is often taken for granted. However, as anyone who has tried to understand an announcement in a reverberant and noisy railway station knows, obtaining clear and intelligible speech reinforcement in a real acoustic environment is often difficult. The purpose of this section is to review the nature of the speech reinforcement problem from its fundamentals in order to clarify the true nature of the problem. We will examine the problem from the perspective of the sound source, the listener, and the acoustics. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2444
Categorization
- DEFINE: Explains the inverse square law for direct sound, foundational to understanding how distance degrades speech comprehension.
- corroborated: 4 independent passages support this claim — David Howard, Jamie Angus, coustics and Psychoacoustics, 2434; David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2444
- XREF: connects to: Speech intelligibility in rooms can be predicted from fluctuation strength — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 2059; Optimal reverberation and strength targets differ sharply by music type; Early room reflections benefit speech intelligibility as much as raised direct sound level — Toole, Floyd E, Sound reproduction- the acoustics and…, 557 (+12 more)
Broader Connections
- Speech intelligibility indexes average signal-to-noise ratio across critical bands
#expands(0.75) — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 90