Sound Absorber and Silencer


Duration 2 Tage (2x 8 UE)

Date 25.09.2024 and on demand / 1600 EUR

Location Dresden/ Inhouse/ Web

Speaker Prof. J. Hübelt and S. Kluth

Precondition Fundamentals of Acoustics (recommended)

Focus of the seminar Acoustic design of mufflers and sound absorbers is the acoustic dimensioning of silencers and mufflers for machines and devices, vehicles, ventilation systems, power plants and other noise emitting systems with ducts. With respect to the optimization of the acoustic efficiency of absorption mufflers, it is dealt with the characterization and the physical modeling of porous absorbers in detail.

The focus of the second day of the training course lies on the computational acoustic design of sound absorbers, silencers and mufflers in combination with the evaluation of silencers and mufflers by means of acoustic measurements. Thereby different tools of the Gesellschaft für Akustikforschung are applied.

1. Sound absorber

  • porous absorbers (mineral wool, melamine foams, hollow metal sphere structures, open-porous asphalts, fills, etc.)
    • characteristic values of materials (measuring method, airflow resistivity, porosity, tortuosity, …)
    • acoustic design of sound absorbers right at the wall as well as at a distance to the wall
    • covers of absorbers (perforated plates, …)
    • acoustic design of sound absorbing curtains
  • micro-perforated sound absorbers
  • plate-shaped oscillators and perforated plate-shaped oscillators
  • Helmholtz resonators
  • resonator with dimension equal to fourth of wave length
  • combined absorbers

2. Silencers and mufflers

  • absorption muffler
    • types of construction
    • effectiveness (frequency response, limiting effect, …)
    • fields of application
    • approximate solution of Piening
    • flow noise
    • pressure drop
    • exact solution
  • reflection muffler
    • types of construction
    • effectiveness
    • fields of application
    • insertion loss at an abrupt change of cross section
    • insertion loss of a chamber
  • resonance muffler
    • types of construction
    • effectiveness
    • fields of application

3. Computational design of silencers and mufflers and evaluation by means of acoustic measurements

  • design of sound absorbers with analysis software
  • acoustic evaluation of porous materials by measurement of airflow resistance with airflow resistivity meter AcoustiFlow®
  • acoustic design of silencers and mufflers by means of silencer software AcoustiCalc®
  • measurement of spectral transmission loss of silencers and mufflers in the test setup for mufflers AcoustiTube® HighTemp