Archives: Seminare

ACENA Posttype für Seminare

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

Fundamentals of Acoustics


Duration 1 Day (1 x 8 UE)

Date 24.09.2024 und auf Anfrage / 820,- EUR

Location Dresden/ Inhouse/ Web

Speaker Prof. J. Hübelt

Precondition -

Content of the seminar Basics of technical acoustics is the definition of the most important physical quantities and terms in the field of acoustics. In the following, the basic effects of sound propagation in fluids are shown. The basics of room acoustics are presented in the last past of the training course.

All along, practical experiments and exemplary measurements are carried out to demonstrate the gained knowledge in the field of technical acoustics.

1. 1. Basics – Signals und sound

  • characteristics of signals and sound
    • description of harmonic quantities
    • statistical quantities for describing signals
  • sound pressure level (SPL)
    • definition of sound pressure level
    • summation of sound pressure levels
    • averaging
  • Bandpass filter – Third octave and octave filters
  • Sound power and sound power level

2. Perception and evaluation of sound signals

  • weighting in frequency domain
  • weighting in time domain
  • rating of sound, rating level according to TA Lärm

3. Sound propagation in free field

  • plane wave
  • impedance
  • sound intensity
  • spherical wave

4. Sound reflection, sound transmission and sound absorption

  • power balance
  • surface impedance und reflection factor
  • sound insulation

5. Fundamentals of room acoustics

  • reverberation time of rooms
  • reverberation time and sound absorption
  • sound power and sound pressure in the diffuse sound field
  • sound pressure level and sound power level in rooms
  • technical sound absorbers