科研之友
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摘要
The design of panels improving both sound absorption and insulation performance over a wide frequency range is a problem of considerable practical interest for transport and building industries. In this work, an analytical method for predicting both the absorption coefficient and the transmission loss of hybrid active/passive multilayered cells and the associated experimental investigation are presented. These cells combine passive and active control by using passive layers and an active plate. Passive layers consist of absorbing materials located on the reception side in order to increase absorption over a wide frequency range. The active plate vibrates as a secondary source in order to reduce sound transmission at low and/or at resonance frequencies. To validate the analytical approach, measurement methods in ducts based on the scattering-matrix description are applied to characterise three types of system: (i)-passive discontinuities such as multilayered sandwiches including porous layers (ii)-active discontinuities here the active plate playing the secondary source role, (iii)-hybrid cells equipped with active control system. For these three cases, the correspondence between theoretical simulations and experimental results is satisfactory.
- 出版日期2011-8
