Signal delays can make flat arrays behave like curved ones.

Evidence

Conventional CBT arrays require a driver configuration that conforms to either a spherical-cap curved surface or a circular arc. Keele also showed how CBT arrays can be implemented in flat-panel or straight-line array configurations using signal delays and Legendre function shading of the driver amplitudes. CBT arrays do not require any signal processing except for simple frequency-independent shifts in loudspeaker level. This is in contrast with conventional constant-beamwidth flat-panel and straight-line designs, which require strongly frequency-dependent signal processing. — David Howard, Jamie Angus, coustics and Psychoacoustics, 2902

Categorization

• XREF: Connects to the book’s earlier treatment of signal delay and phase as the mechanism producing spherical wavefronts from planar sources.
• SEED: Angle: ‘the delay trick’ as a general design pattern — cheap, frequency-independent control beating costly frequency-dependent processing across engineering domains.