Walls and corners near a sound source increase its power output

Evidence

Averaging over a range of short wavelengths (the source is far from the wall), the sound is still N times louder inside the wedge than it would have been without the wedge, but this is just the simple confinement effect; the average total power from the source is not increased for short wavelengths. … We have just shown that walls and floors can actually amplify a nearby source, in addition to directing its energy. This is done by extracting more power from the source, which is wasting most of its power anyway, such as by heating up the coils and magnets that drive a speaker cone electrically. — Eric J. Heller, Why You Hear What You Hear- An…, 524

Categorization

• XREF: connects to: Operating with three nearby boundaries gives a fixed 9 dB low-frequency rise — David Howard, Jamie Angus, coustics and Psychoacoustics, 2193