Radiation directivity depends on wavelength relative to source size

Evidence

This appendix has presented the basic Fourier relationship between the far-field polar response and the near-field illumination of the aperture. It has demonstrated its utility in a variety of electroacoustic applications. In particular, it is possible to derive some useful relationships between the size of the speaker, with respect to wavelength, and its directivity performance versus frequency—in particular that for directivity, size really does matter! — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2946 (#corroborates, via linked claim)

Categorization

• XREF: connects to: A piston’s radiation efficiency depends on size relative to wavelength, not absolute size; Extended sources twinkle less than point sources, revealing their size; Shorter wavelengths scatter more strongly from small objects than longer ones do. (+5 more)

Related

• Directivity depends on wavelengths fitting across the radiating aperture (similarity 0.95)
• Acoustic wavelength size relative to objects governs how sound interacts with them (similarity 0.94)
• A piston’s radiation efficiency depends on size relative to wavelength, not absolute size (similarity 0.91)
• Larger speaker size relative to wavelength enables higher directivity (similarity 0.90)
• At low frequencies only drivers and ports define a loudspeaker’s effective source size (similarity 0.89)
• Reflection and diffraction of sound both depend on object size relative to wavelength (similarity 0.84)
• A speaker’s coverage angle roughly doubles for each octave below its minimum directivity frequency. (similarity 0.84)
• Small loudspeakers radiate omnidirectionally because they are small relative to wavelength (similarity 0.83)
• Sound-radiation efficiency depends on piston size relative to wavelength, not absolute size (similarity 0.82)
• Large radiating surfaces become highly directional at high frequencies (similarity 0.82)
• Increasing speaker directivity reduces the reverberant field like a tone control does (similarity 0.82)
• Whether a surface reflects or scatters waves depends on roughness relative to wavelength (similarity 0.81)
• Speaker drivers’ directivity at high frequencies causes spectral dips in the reverberant field (similarity 0.80)
• Sound scatters or diffracts around loudspeakers based on wavelength relative to size (similarity 0.79)
• Free-field radiation requires the source to be far from reflecting surfaces (similarity 0.79)

Broader Connections

• Directivity depends on wavelengths fitting across the radiating aperture #corroborates (0.95)
• Larger speaker size relative to wavelength enables higher directivity #corroborates (0.90) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2946
• Reflection and diffraction of sound both depend on object size relative to wavelength #expands (0.85)
• Acoustic wavelength size relative to objects governs how sound interacts with them #expands (0.85)