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2 2022

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Research on the influence of airflow resistance of layered porous structures on the sound absorption coefficient

Flach Artur

Vibrations in Physical Systems

2022

Vol. 33, nr 3

art. no. 2022311

The paper presents the research on the influence of airflow resistance on the sound absorption coefficient of layered porous structures. For the calculation of the sound absorption coefficient, the models of layered sound-absorbing structures were developed with the use of numerical computational models. Using the developed models, optimization was carried out to maximize the average sound absorption coefficient of the structures for a given frequency range. As a result of the research, the dependence of the change in airflow resistance for the successive layers of the material was determined. The results of the work will be particularly useful in the design of wedges used in anechoic chambers.

Metrological capabilities of the acoustic testing laboratory - small anechoic chamber at the AGH Department of Mechanics and Vibroacoustics

Kłaczyński Maciej, Wszołek Wiesław

Vibrations in Physical Systems

2022

Vol. 33, nr 2

art. no. 2022217

The small anechoic chamber is part of the research facilities of the Department of Mechanics and Vibroacoustics in AGH University of Science and Technology in Krakow and is a room corresponding to a free field, whose walls, ceiling and floor provide both very good sound absorption and isolation from external interference. The dimensions of the free space inside the chamber are 4.4 m x 3.8 m. x 3.6 m. The chamber was commissioned in the mid-1980s and has not undergone upgrades since. In December 2021, the upgrade of the small anechoic chamber was completed. As particularly important was the replacement of 5.5 thousand pieces of acoustic wedges made of polyurethane foam, which due to the aging process lost their sound-absorbing properties, for wedges made of mineral wool with glass fiber, adjustment of lighting inside the chamber to current standards, as well as equipping the chamber with a signal crossover and devices to regulate and monitor meteorological conditions inside the chamber. The paper presents a study of the properties of the small anechoic chamber in accordance with accepted standards for this type of rooms and its current research capabilities in the field of vibroacoustics in technology and medicine.