The fraction of sound arriving at a surface that is absorbed by the material. This controls how long it takes for the reverb to decay, with higher absorption leading to shorter reverberation times. This is the Sabine absorption coefficient, which is the absorption averaged over all angles of incidence. The absorption coefficient is the opposite of the reflection coefficient (1 - absorption). The default absorption is 0.1.

The fraction of sound arriving at a surface that is transmitted through the material. This value is in the range 0 to 1, where 0 indicates a material that is acoustically opaque, and 1 indicates a material that is acoustically transparent. To preserve energy in the simulation, the following condition must hold: (1 - absorption + transmission) <= 1. If this condition is not met, the transmission and absorption coefficients will be modified to enforce energy conservation. The default transmission is 0. Note that increasing the transmission coefficient has the effect of reducing the reverberation time because it allows some of the sound to escape the geometry.

The fraction of sound arriving at a surface that is scattered. The scattering coefficient describes how rough or smooth the surface is for sound of a given frequency. A value of 0 indicates a perfectly mirror-like (specular) reflection, while a value of 1 indicates a perfectly diffuse/matte reflection. The default value is 0.5. The impact of the scattering coefficient on the audio is subtle, and it primarily affects the early reflections.