Diffusion (acoustics)

[1] Maximum length sequence based diffusors are made of strips of material with two different depths.

The width of the strips is smaller than or equal to quarter the wavelength of the frequency where the maximum scattering effect is desired.

Ideally, small vertical walls are placed between lower strips, improving the scattering effect in the case of tangential sound incidence.

The bandwidth of these devices is rather limited; at one octave above the design frequency, diffusor efficiency drops to that of a flat surface.

The new goal was to find a new surface geometry that would combine the excellent diffusion characteristics of MLS designs with wider bandwidth.

This is done by the creation of a grid, whose cavities have wells of varying depth, according to the matrix addition of two quadratic sequences equal or proportionate to those of a regular diffusor.