@article {Randeberg:2002:1610-1928:507,
title = "Adjustable Slitted Panel Absorber",
journal = "Acta Acustica united with Acustica",
parent_itemid = "infobike://dav/aaua",
publishercode ="dav",
year = "2002",
volume = "88",
number = "4",
publication date ="2002-07-01T00:00:00",
pages = "507-512",
itemtype = "ARTICLE",
issn = "1610-1928",
url = "https://www.ingentaconnect.com/content/dav/aaua/2002/00000088/00000004/art00006",
author = "Randeberg, R. T.",
abstract = "Currently, there is a great interest in panel absorber design where porous components are excluded due to environmental and cleaning considerations. For such absorbers, the challenge is to increase the natural, viscous losses to attain an acceptable absorption bandwidth. This paper
discusses a revised version of an earlier concept presented in this journal [1], where the viscous energy dissipation has been enhanced by the use of non-traditional design of the perforations. The concept is a double perforated panel, consisting of two parallel, perforated plates separated
by a small distance, typically 0.10.3 mm. The main part of the energy dissipation takes place in the small gap between the plates. The absorber can be designed to be adjustable, allowing the lateral distance between the slits in the two plates to be varied. This offers two special features:
The maximum absorption coefficient can be adjusted from unity to almost zero, and the resonance frequency can be shifted. A frequency shift of one octave at normal sound incidence has been obtained.",
}