Sound Diffusers with Fabric Covering

Fabric covering is often used by designers, as it can easily mask acoustic structures that do not match
an interior. However, in the case of sound diffusers based on change in the phase of the reflected wave, the
use of fabric covering is not without its effect on acoustics. It reduces the effectiveness of these structures
and raises acoustic absorption. In the paper, the authors analyzed the acoustical properties of a selected
fabric used to cover sound diffusers. Sound absorption and scattering coefficients for a system composed
of sound diffusers and a fabric situated at different distances d were measured. The results were compared
to the sound absorption predicted on the basis of Kuttruff’s and Mechel’s theoretical models. Analysis
of the results indicates that the fabric has a significant influence on the system’s acoustic parameters. It
is also observed, that fabric applied directly on a phase grating diffuser, produces higher absorption than
when it is at some distance from it.