Tubo de impedância para baixas frequências: construção e validação

Rodolfo Thomazelli; Stelamaris Rolla Bertoli

doi:10.55753/aev.v34e51.81

Authors

Rodolfo Thomazelli Faculdade de Engenharia Civil, Arquitetura e Urbanismo, Universidade Estadual de Campinas
Stelamaris Rolla Bertoli Faculdade de Engenharia Civil, Arquitetura e Urbanismo, Universidade Estadual de Campinas

DOI:

https://doi.org/10.55753/aev.v34e51.81

Keywords:

impedance tube, sound absorption, low frequency, Helmholtz absorbers

Abstract

For the determination of the sound absorption coefficients of acoustic materials there are established methods, such as those employed in reverberant room and impedance tube. For the development of sound absorption materials, the impedance tube methods - such as standing wave and transfer function - are more advantageous because they require comparatively smaller samples. The transfer function method is considered more practical for measurement processes as it allows the sound absorption coefficient to be obtained over a continuous frequency range. The authors of this paper are developing research on Helmholtz absorbers to operate at frequencies below 100 Hz. Due to the peculiarities of the object, for its acoustic characterization it was necessary to construct an impedance tube configured to receive the transfer function method, and able to meet the dimensions of the samples and the desired frequency range. This article aims to present the theoretical foundations and technical requirements that were used in the development of the apparatus, as well as the respective construction process. Also included in the article is the apparatus validation process, which showed that the experiments provides results with an average deviation of 1,9 Hz in relation to the predicted theoretical model.

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