Two loudspeakers can synthesize a credible 5-channel surround illusion

Evidence

Such processing converts the phase or time delays between the loudspeakers at low frequencies to a perception of level differences between the ears, and at high frequencies the perception remains as a time difference in the signal between the ears. This effect makes the virtual source direction depend on the signal itself (Cooper, 1987; Lipshitz, 1986). The produced binaural cues vary with frequency, and different cues suggest different directions for virtual sources (Pulkki, 2001b). The cue may thus generate a ‘spread’ perception of the direction of sound, which is desirable in some cases. The effect is also dependent on listening position. For example, if the sound signal is delayed by 1 ms in one loudspeaker, the listener can compensate for the delay by moving a bit towards the delayed loudspeaker. Time delay panning thus resembles spaced microphone techniques, since the spacing between the microphones causes time delays between microphone signals and since the resulting spatial image is similar. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1911 (#expands, via linked claim)

Categorization

• XREF: connects to: Blind testing found 20% preferred synthesized phantom surround over real speakers; Stereo loudspeakers create directional illusion through summed phase shifts mimicking time delays — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1911; Spatial audio systems create illusions of direction and space rather than reproducing them exactly (+3 more)

Broader Connections

• Stereo loudspeakers create directional illusion through summed phase shifts mimicking time delays #expands (0.85) — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1911
• Spatial audio systems create illusions of direction and space rather than reproducing them exactly #expands (0.80)
• Ambisonic reproduction synthesizes a sound field through codependent speaker arrays rather than direction-assigned channels #exemplifies (0.75)
• Wide-dispersion speakers plus room reflections create listener envelopment. #expands (0.72)