Direct sound carries signal information uncontaminated and governs speech intelligibility

Evidence

The direct component is important because it carries the information in the signal in an uncontaminated form. Therefore a high level of direct sound is required for a clear sound and good intelligibility of speech. The direct sound also behaves in the same way as sound in free space, because it has not yet interacted with any boundaries. This means that we can use the equation for the intensity of a free space wave some distance from the source Figure 6. — David Howard, Jamie Angus, coustics and Psychoacoustics, 1729

Categorization

• DEFINE: Introduces the core concept of ‘direct sound’ and its role in intelligibility, foundational for the reader’s understanding of room acoustics.
• corroborated: 4 independent passages support this claim — David Howard, Jamie Angus, coustics and Psychoacoustics, 1729
• 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; High-pitched soprano singing sacrifices intelligibility for audibility; The first-arriving direct sound perceptually dominates despite carrying less energy (+10 more)

Broader Connections

• Speech intelligibility depends on high direct-to-reverberant sound ratios #expands (0.95) — David Howard, Jamie Angus, coustics and Psychoacoustics, 2434
• Adding more loudspeakers can worsen speech intelligibility by shrinking critical distance #qualifies (0.75) — David Howard, Jamie Angus, coustics and Psychoacoustics, 2454