Diffusivity (acoustics)
Diffusivity (dispersion), or more specifically sound diffusivity generally describes the degree of distribution of reflected sound of a source in space and over time.
definition
The term is closely related to the subjective idea of a diffuse room sound and is not always applied in the same way. There is no mathematical description of a quantity and consequently no assigned unit .
Sometimes a distinction is made between:
- local diffusivity , usually defined as the uniformity of sound incidence over the direction of sound incidence at a specific location, and
- Temporal diffusion , the distribution of the reflected sound signals at the measurement location over time.
Both increase with the variety of reflection possibilities in a room and its size.
Causes and application
Sound diffusivity describes the room acoustic properties that result when the boundary surfaces of a room and the objects contained in it do not reflect in only "one" direction ("regular") like a mirror, but diffusely, ie. H. more or less in all directions (see also statistical or diffuse sound field ). Such diffuse fields are required in statistical room acoustics in order to e.g. B. To plan construction work for concert halls . They also play an important role for certain acoustic measurement methods.
An increase in the diffusivity in order to effect an apparent enlargement of the room is possible by using artificial electronic reverb effects from loudspeakers .
In room acoustics and sound engineering , a high degree of diffusivity is achieved through targeted guidance and mechanical dispersion of the sound waves. This can be done through simple, curved interfaces or the use of diffusers .
In order to ensure a balanced acoustic listening room or recording room post-treatment, the diffusivity should always be achieved by means of reflection and at the same time also with absorption .
Web links
- Diffusivity (PDF file; 2.76 MB)
- Understanding sound diffusion - engl. (PDF file; 82 kB)