Uncorrelated ambient signals create an impression of directionless surround sound.

Evidence

The ambient sounds and sound effects are diffused via rear-mounted speakers. Originally they were not supposed to provide directional effects and were deliberately designed and fed signals that minimized their correlation with each other and the front speakers. The effect of this was to fool the hearing system into perceiving the sound as all around with no specific direction. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2218

Categorization

• DEFINE: Explains the design principle behind how surround ambience achieves its diffuse, enveloping quality.
• corroborated: 2 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2218
• XREF: connects to: Dipole surround speakers degraded direct sound without creating effective diffuse fields.; Excess uncorrelated rear-wall sound can destroy the phantom center image — , Toole, Floyd E - Sound reproduction-…, 702; Uncorrelated noise from surround speakers creates enveloping source perception. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1914 (+4 more)

Broader Connections

• Spatial envelopment requires uncorrelated ear signals, not a diffuse sound field #corroborates (0.90)
• Late-arriving room sound becomes omnidirectional and uniformly distributed #expands (0.85)
• Spatial audio systems create illusions of direction and space rather than reproducing them exactly #expands (0.80)