Directional Sound

Speaker Diameter - Dispersion ChartDriver Diameter and Piston Beaming Frequency

Here is a quote from “Loudspeaker Design Cookbook – 7th Edition (Vance Dickason) taken from page 8:

“Cone Directivity – As frequency increases all speakers become more directive and the high frequencies begin to “beam” like the light from an automobile headlight. At frequencies where the wavelength of sound (wavelength being equal to the speed of sound divided by the frequency = C/F, i.e. 1kHz has a wavelength of 1.13 feet) is large compared to the circumference of the cone (about 3 times the diameter), the radiation is spherical. As the frequency increases to the point where wavelength is equal to the circumference of the driver or smaller, the radiation patter becomes progressively narrower. The chart in FIG. 0.14 gives the =6db off-axis points for different diameter speaker diaphragms (after Daniels with changes, JBL Pro Soundwaves, Fall 1988)

WIKI – Directional Sound


“The larger the speaker array, the more directional, and the smaller the size of the speaker array, the less directional it is. This is fundamental physics, and cannot be bypassed”

This is a link from that page and explains some higher reasoning behind the concept if you’re the type of person who can understand such things:

WIKI – Huygens Fresnel Principle