Studio Acoustics 8 min read Updated: October 2026

Acoustic Diffusers: Schroeder, Quadratic Residue (QRD) & 2D Skyline Diffusers

Covering every surface of a recording studio with acoustic absorption produces a claustrophobic, lifeless environment known as an anechoic chamber. Acoustic diffusion preserves acoustic energy in the room while scattering reflections evenly across time and spatial angles.

Schroeder Quadratic Residue Diffusers (QRD)

In the 1970s, mathematical physicist Manfred Schroeder discovered that number-theoretic sequences could create acoustic surfaces with uniform energy scattering. A 1D QRD diffuser features an array of wells of varying depths separated by thin dividers:

$$d_n = \frac{c}{2 f_r} \cdot \frac{(n^2 \bmod N)}{N}$$

Schroeder QRD well depth formula based on prime number $N$ and design frequency $f_r$

2D Skyline Diffusers

Two-dimensional Skyline diffusers feature columns of varying heights organized in a grid. They scatter sound hemispherical in both horizontal and vertical planes, ideal for back walls and low ceilings in compact production suites.

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