Equal distances from two loudspeakers eliminate all room-induced destructive interference

Evidence

The idea seems to have originated with Goertz et al. (2001), who used an arrangement of subwoofers on the front wall, generating an approximation of a plane wave that propagates to the rear of the room where a similar arrangement of subwoofers, appropriately delayed and polarity inverted, cancels the wave when it arrives. Ideally this eliminates standing waves and everyone in the room should hear good bass. It requires a perfectly rectangular room and at least four subwoofers to work well. The scheme was called double bass array (DBA). — Toole, Floyd E, Sound reproduction- the acoustics and…, 1604 (#expands, via linked claim)

Categorization

• XREF: connects to: Superposed sounds cancel or amplify locally without changing each other; Concentrating loudspeakers at one point yields the best direct-to-reverberant ratio for a space; Loudspeakers and rooms function together as a single audible system (+2 more)

Related

• Delayed, inverted subwoofer arrays can cancel standing waves in rectangular rooms (similarity 0.87)
• Subwoofer mode cancellation needs no equalization to fix boom (similarity 0.83)
• Subwoofer placement itself can be optimized alongside DSP settings (similarity 0.83)
• Optimal woofer placement makes boundary distances as different and non-multiple as possible (similarity 0.82)
• Opposite-polarity subwoofers can null a specific room mode’s coupling (similarity 0.82)
• Optimized multi-sub systems can use much smaller subs at some locations (similarity 0.82)
• Inverting a signal cancels sound at all frequencies when paths are equal (similarity 0.82)
• Inverted signals cancel at all frequencies while delayed signals cancel selectively by frequency (similarity 0.81)
• Boundary distances tuned to be unequal and non-multiples minimize frequency-response variations (similarity 0.81)
• Optimizing any two of room, subwoofer, and seating yields the third (similarity 0.81)
• Loudspeakers and rooms function together as a single audible system (similarity 0.80)
• Wide-dispersion speakers plus room reflections create listener envelopment. (similarity 0.80)
• Room reverberant fields typically rise in bass, necessitating bandwidth-matched equalizer cuts for distant miking (similarity 0.80)
• Most loudspeakers need equalization to correct low-frequency room resonances (similarity 0.80)
• Multiple identical subwoofers reduce seat-to-seat bass variation (similarity 0.79)

Broader Connections

• Loudspeakers and rooms function together as a single audible system #expands (0.85)
• Delayed, inverted subwoofer arrays can cancel standing waves in rectangular rooms #expands (0.80) — Toole, Floyd E, Sound reproduction- the acoustics and…, 1604
• Concentrating loudspeakers at one point yields the best direct-to-reverberant ratio for a space #complicates (0.75)
• Mixing consoles must correct for amplitude variation arising from loudspeaker phase and level interactions #expands (0.75)