Controlled boundary measurements confirm the predicted 6 dB per solid-angle-halving gain
Evidence
Practical measurements confirm the theory. Figure 13.2 shows measurements made at the NRCC in Ottawa, in the mid 1980s, in an anechoic chamber, and outdoors, in a parking lot adjacent to an isolated flat-sided building. The only reflecting surfaces were the adjacent boundaries. The loudspeaker was a conventional 12-inch (305 mm) driver in a closed box, about 17 inches (432 mm) on a side. Noise problems prevented the acquisition of data below about 35 Hz, and a technical problem resulted in the corruption of the 2π steradian data, but the trend is very evident. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1458
Categorization
Category: Factual Claims
- SHARE: Worth sending to an audio-measurement colleague interested in experimental validation setups and their practical pitfalls (noise floor, corrupted 2π data).
Related
- Concentrating sound into a smaller solid angle raises horn sensitivity (similarity 0.79)
- Each added boundary surface boosts sound intensity by 3 dB up to three boundaries (similarity 0.78)
Broader Connections
- Concentrating sound into a smaller solid angle raises horn sensitivity
#corroborates(0.90) — David Howard, Jamie Angus, coustics and Psychoacoustics, 2519 - Each added perpendicular boundary halves the solid angle and adds a reflected acoustical image
#expands(0.85) — Toole, Floyd E, Sound reproduction- the acoustics and…, 1455 - Each added boundary surface boosts sound intensity by 3 dB up to three boundaries
#corroborates(0.85) — David Howard, Jamie Angus, coustics and Psychoacoustics, 313 - Coherent summation of aligned horns lets off-axis points act on-axis
#corroborates(0.75) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2533