Wide-dispersion speakers plus room reflections create listener envelopment.

Evidence

There is very good news. Large numbers of channels are not necessary to provide excellent facsimiles or reconstructions of enveloping sound fields. This is true whether the evaluating metric is subjective or objective. The optimal selection of four or five channels and loudspeakers can provide performance very similar to circular arrays of 12 or 24 loudspeakers. — , Toole, Floyd E - Sound reproduction-…, 1709 (#corroborates, via linked claim)

Categorization

• XREF: connects to: Reflecting surfaces can extract wasted energy from an inefficient sound source.; Loudspeakers and rooms function together as a single audible system; Concentrating loudspeakers at one point yields the best direct-to-reverberant ratio for a space (+12 more)

Broader Connections

• Loudspeakers and rooms function together as a single audible system #expands (0.85)
• Four or five well-placed loudspeakers match the envelopment of 12-to-24 channel arrays #corroborates (0.80) — , Toole, Floyd E - Sound reproduction-…, 1709
• Room boundaries alter loudspeaker output through reflected image sources #expands (0.78)
• Concentrating loudspeakers at one point yields the best direct-to-reverberant ratio for a space #qualifies (0.75)
• Early side-wall reflections range neutral to beneficial with well-designed loudspeakers #corroborates (0.72) — Toole, Floyd E, Sound reproduction- the acoustics and…, 845