Large radiating surfaces become highly directional at high frequencies

Evidence

Because directivity is determined by the wavelength relative to the size of the radiating surface, a large surface radiating the full audio bandwidth becomes progressively more directional with increasing frequency. The usual solution for the directivity problem is to subdivide the panel into progressively smaller areas, radiating successively higher frequencies, using crossovers. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1014

Categorization

• DEFINE: Explains the wavelength-to-surface-size ratio that underlies loudspeaker directivity.