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Einfluß der Bandbreite und des Spektrums auf die Dämpfung von Schalldämpfern in Kanälen

: Ackermann, U.

KI - Klima, Kälte, Heizung (1989), No.1, pp.16-19
ISSN: 0024-7251
ISSN: 0172-1984
Journal Article
Fraunhofer IBP ()
air flow noise; Bandbreite; Daempfung; DIN 45646; Druckverlust; Oktavanalyse; RLT-Anlage; Schalldämpfer; sound absorption efficiency; Strömungsgeräusch

The new DIN 45646 (1) specifies test bench measurements of the sound absorption efficiency (2), air flow noise (3) and pressure loss of sound absorbers (4). The latter, as a rule, are slotted-link sound absorbers for HVAC systems. The DIN standard specifies tierce steps for the sound absorption measurements, although the user may find other band widths better suited to his purpose. For example, narrow-band analysis may be useful for dimensioning narrow-band absorbers. Wide-band octave analysis, on the other hand, is often preferred for practical applications, e.g. immission calculations. The measured absorption levels depend on the spectrum of the sound field to be attenuated and also on the filter band width used for analyzing the microphone signal. Narrow-band results therefore cannot easily be applied to tierce steps, nor can tierce step results be applied to octave steps. Two examples show how the sound absorption efficiencies are influenced by band width and spectrum.