Operating with three nearby boundaries gives a fixed 9 dB low-frequency rise

Evidence

If the dimensions are the same then one has a low-frequency response that rises 9 dB above the mid-band response, and that has significant variation over the frequency range – in particular when the distance between the loudspeaker and the boundaries is just above a quarter of a wavelength … By placing the speaker carefully, with respect to the boundaries, one can eliminate some of the variation in the response. However, one still has a 9 dB rise in response at low frequencies. This is well known and the 9 dB rise at low frequencies is inherent in operating in an environment with three boundaries. — David Howard, Jamie Angus, coustics and Psychoacoustics, 2193

Categorization

• DEFINE: Defines the boundary-interaction effect principle governing loudspeaker placement.
• XREF: connects to: Operating a loudspeaker near three room boundaries imposes a 9 dB low-frequency rise — David Howard, Jamie Angus, coustics and Psychoacoustics, 2193; Boundary placement boosts low-frequency output by 6 dB per solid-angle halving. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1459; Walls and corners near a sound source increase its power output — Eric J. Heller, Why You Hear What You Hear- An…, 524 (+4 more)

Broader Connections

• Operating a loudspeaker near three room boundaries imposes a 9 dB low-frequency rise #expands (0.98) — David Howard, Jamie Angus, coustics and Psychoacoustics, 2193
• Controlled measurements confirm the theoretical boundary-gain relationships at low frequencies #corroborates (0.90)
• Boundary placement boosts low-frequency output by 6 dB per solid-angle halving. #expands (0.88) — Toole, Floyd E, Sound reproduction- the acoustics and…, 1459
• Flush-mounting a speaker in a wall reduces the low-frequency rise to 6 dB #qualifies (0.85) — David Howard, Jamie Angus, coustics and Psychoacoustics, 2194
• Boundary placement boosts sound intensity 3 dB per boundary by increasing directivity #contradicts (0.85) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 321
• Each added boundary surface boosts sound intensity by 3 dB up to three boundaries #contradicts (0.82)
• Walls and corners near a sound source increase its power output #qualifies (0.78) — Eric J. Heller, Why You Hear What You Hear- An…, 524