Computation of Absorptive Silencers


By means of the software programme compas (computation of absorptive silencers) the attenuation of absorptive silencers can be computed according to analytical methods and has been available as a DOS version for a long time. Now it is available in a Windows™ version as the first module of the new software family for acoustics of Fraunhofer IBP. The programme computes according to the theory of sound propagation in lined absorbent ducts with superimposed flow the propagation loss and reflection loss. The sum of these two attenuation parts results in the insertion loss of the silencer, as it is measured in the test facility according to ISO 7235.

Scope of service

Besides the insertion loss for splitter silencers, it is possible to compute with compas silencers of different geometries as well as further properties:

  • the attenuation of splitter silencers and tubular silencers (without pod) as well as quadratic rectangular ducts lined on all sides
  • two-layer absorbers with the integration of covers such as perforated sheet metal of fleece
  • the sond power Lw of the flow noise
  • the sond power Lw of the flow noise
  • the pressure loss Δp and pressure loss coefficient ζ of the silencer
  • energy costs due to pressure losses
  • the computation of all parameters in dependence of temperature and super-imposed flow.


Our offer:
Apply compas for the computation of silencers for your projects and developments. The programme is available as single od multiple licence. We are looking forward to sending you a demo version on CD.

System requirements:
Windows XP