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Miniature omnidirectional sound sources used in acoustic scale modeling - measurements and validation

Chojnacki Bartłomiej

Vibrations in Physical Systems

2022

Vol. 33, nr 2

art. no. 2022201

Acoustic measurements such as scale modeling measurements require a particular type of miniature omnidirectional sound source. The most important aspects of those devices are small sizes (usually below 100 mm in diameter) and different frequency ranges compared to traditional, omnidirectional sound sources used in room acoustics. The required frequency range differs regarding the used scale factor in different models, which leads to the troubles in frequent source changes and the need for a unique source design for every model. The project will present the recent achievement in miniature omnidirectional sound sources development. The optimal sound sources for the given measurement functions were developed based on the previous numerical simulations and experiments such as FEM sound directivity simulations or transducers' parameters tolerance testing. The sound sources presented are used for applications such as acoustic sound insulation scale measurements (frequency range 800 ÷ 63 000 Hz), scaled reverberation chamber measurements (300 ÷ 80 000 Hz), or acoustic reduction models measurements (400 ÷ 70 000 Hz). The paper will cover a detailed technical explanation of the laboratory environment's source construction aspects and validation measurements.

Measurement of perforated panels at a scaled measurement setup

Baruch Katarzyna, Kamisiński Tadeusz, Majchrzak Aleksandra

Vibrations in Physical Systems

2019

Vol. 30, nr 1

art. no. 2019114

In the paper, the authors present an ongoing research on the absorption and measurement uncertainty of perforated panels made at different scales. Knowing the similarity criteria describing the relation between a full-size perforated panel and its scaled equivalent, it is possible to conduct the measurements of the elements of significantly reduced size - with an area not exceeding 0.2 m2. This procedure notably decreases the costs resulting from the production, transportation and storing the measurement samples. At the same time, the obtained values of sound absorption coefficient measured for the samples at 1:8 scale will characterize their full-size equivalents of geometry changed according to the derived similarity criteria. The paper discusses the possibilities of measurement of scaled samples.