User Guide#
Zorba is a program that can calculate the acoustic absorption performance of common materials and some simple systems such as slot or slat absorbers, or absorbers covered with a perforated facing or panel absorbers.
Zorba calculates the acoustic impedance, the normal incidence absorption coefficient and, within certain limitations, the random incidence absorption coefficents of common materials and systems.
Slatted and perforated absorbers
It is important to be able to predict the sound absorption properties of slatted and perforated absorbers.
These types of absorbers are frequently used to control the acoustics of rooms, and it is often found that there is no test data available for a particular design, or it is necessary to design an absorber to achieve specific characteristics.
Model assumptions#
Within certain limits good agreement is obtained between predictions and experiments.
- Materials are assumed to be locally reacting, with properties determined by their static flow resistivity.
- The effect of facings is modelled by adding the reactance of the facing to the normal incidence impedance of the material.
- The random incidence coefficients are predicted from normal incidence impedance using diffraction theory.
References#
The absorption of sound is a topic on which many text books have been written.
This help file is not a substitute for learning about the theory of sound absorption. Users should be aware of the general principles of acousic absorption as discussed, for example, in the following texts.
Author |
Title |
|---|---|
| Beranek | Noise and Vibration Control (1971) |
| Beranek | Noise and Vibration Control Engineering (1992) |
| Meyer & Newman | Physical Principles of Acoustics (1970) |
| Allard | Propagation of Sound in Porous Media (1994) |