A speaker’s coverage angle roughly doubles for each octave below its minimum directivity frequency.

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 (#complicates, via linked claim)

Categorization

• XREF: connects to: Larger speaker size relative to wavelength enables higher directivity — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2946; Increasing speaker directivity reduces the reverberant field like a tone control does; Advertised speaker directivity specs can be meaningless for the speech band.

Related

• Larger speaker size relative to wavelength enables higher directivity (similarity 0.92)
• Increasing speaker directivity reduces the reverberant field like a tone control does (similarity 0.91)
• Speaker drivers’ directivity at high frequencies causes spectral dips in the reverberant field (similarity 0.91)
• At low frequencies only drivers and ports define a loudspeaker’s effective source size (similarity 0.90)
• Advertised speaker directivity specs can be meaningless for the speech band. (similarity 0.87)
• Acoustic wavelength size relative to objects governs how sound interacts with them (similarity 0.86)
• Directivity depends on wavelengths fitting across the radiating aperture (similarity 0.86)
• Radiation directivity depends on wavelength relative to source size (similarity 0.84)
• Speaker size dictates the lowest frequency sustaining a given coverage angle (similarity 0.82)
• Large radiating surfaces become highly directional at high frequencies (similarity 0.82)
• Digital signal processing made constant-directivity array loudspeakers practical and popular (similarity 0.81)
• Sound diffracts strongly only when wavelengths exceed opening size (similarity 0.81)
• Reflection and diffraction of sound both depend on object size relative to wavelength (similarity 0.81)
• As wavelength shrinks below diaphragm size, speakers beam and off-axis sound diverges spectrally (similarity 0.80)
• Loudspeaker enclosure shape and size alter frequency response via diffraction (similarity 0.80)

Broader Connections

• Increasing speaker directivity reduces the reverberant field like a tone control does #complicates (0.75)
• Larger speaker size relative to wavelength enables higher directivity #complicates (0.72) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2946