Active noise cancellation fails at high frequencies due to phase shift limits

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 (#contradicts, via linked claim)

Categorization

• XREF: connects to: Inverted signals cancel at all frequencies while delayed signals cancel selectively by frequency; Subwoofer mode cancellation needs no equalization to fix boom; Hybrid feed-forward and feedback ANC lowers background noise by up to 30 dB (+4 more)

Related

• Inverted signals cancel at all frequencies while delayed signals cancel selectively by frequency (similarity 0.93)
• Inverting a signal cancels sound at all frequencies when paths are equal (similarity 0.93)
• Subwoofer mode cancellation needs no equalization to fix boom (similarity 0.90)
• Delayed, inverted subwoofer arrays can cancel standing waves in rectangular rooms (similarity 0.90)
• Double bass arrays keep high efficiency despite half the units cancelling (similarity 0.82)
• Opposite-polarity subwoofers can null a specific room mode’s coupling (similarity 0.81)
• Active noise cancellation works by adding phase-reversed copies of background noise (similarity 0.81)
• Passive noise cancellation avoids contaminating the wanted signal that active cancellation risks (similarity 0.79)
• Subwoofer placement itself can be optimized alongside DSP settings (similarity 0.78)
• Equal distances from two loudspeakers eliminate all room-induced destructive interference (similarity 0.78)
• Antiphase waveforms cancel when added together (similarity 0.78)

Broader Connections

• Active noise cancellation works by adding phase-reversed copies of background noise #expands (0.90)
• Delayed, inverted subwoofer arrays can cancel standing waves in rectangular rooms #contradicts (0.75) — Toole, Floyd E, Sound reproduction- the acoustics and…, 1604