Controlled measurements confirm the theoretical boundary-gain relationships at low frequencies

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

• XREF: Connects theory to empirical validation protocol — anechoic chamber plus outdoor parking-lot boundary tests, a model of controlled psychoacoustic measurement. — connects to: Operating with three nearby boundaries gives a fixed 9 dB low-frequency rise — David Howard, Jamie Angus, coustics and Psychoacoustics, 2193; Controlled boundary measurements confirm the predicted 6 dB per solid-angle-halving gain; Boundary-induced source power changes scale with distance relative to wavelength — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2134 (+3 more)
• yield-rescued: below the book’s yield-target cutoff, included anyway for connecting to: Operating with three nearby boundaries gives a fixed 9 dB low-frequency rise — David Howard, Jamie Angus, coustics and Psychoacoustics, 2193; Controlled boundary measurements confirm the predicted 6 dB per solid-angle-halving gain; Boundary-induced source power changes scale with distance relative to wavelength — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2134 (+3 more)

Broader Connections

• Controlled boundary measurements confirm the predicted 6 dB per solid-angle-halving gain #expands (0.95)