SOUND TRANSMISSION LOSS OF A DOUBLE-LEAF SOLID-MICROPERFORATED PARTITION UNDER NORMAL INCIDENCE OF ACOUSTIC LOADING

  • Ahmad Yusuf Ismail Universiti Teknikal Malaysia Melaka
Keywords: sound transmission loss, double-leaf, micro-perforated panel

Abstract

The micro-perforated panel (MPP) is recently well-known as an alternative ‘green‘ sound absorber replacing the conventional porous materials. Constructed from a solid panel which provides a non-abrassive structure and also an optically attractive surface, there gives a feasibility to implement such a panel inside a vehicle cabin. This paper is the preliminary study to investigate the sound transmission loss (TL) of a solid panel coupled with a micro-perforated panel to form a doube-leaf partition which is already known as a lightweigth stucture for noise insulation in vehicles and buildings. The mathematical model for the TL subjected to normal incidence of acoustic excitation is derived. The results show that its performance substantially improves at the troublesome frequency of mass-air-mass resonance which occurs in the conventional double-leaf solid partition. This is important particularly for the noise source predominant at low frequencies. This can also be controlled by tuning the hole size and number as well as the air gap between the panels. 

ABSTRAK: Panel bertebuk mikro (micro-perforated panel (MPP)) kebelakangan ini dikenali sebagai alternatif penyerap bunyi yang mesra alam menggantikan bahan berliang lazim. Dibina daripada satu panel padu yang memberikan satu struktur tak lelas dan juga satu permukaan yang menarik, ia memberikan kemungkinan penggunaan panel tersebut di dalam kabin kenderaan. Tesis ini merupakan kajian permulaan dalam mengkaji hilang pancaran bunyi (sound transmission loss (TL)) oleh satu panel padu yang digandingkan dengan satu panel bertebuk mikro. Kaedah ini menghasilkan satu sekatan lembar kembar yang sememangnya dikenali sebagai struktur ringan penebat bunyi di dalam kenderaan dan bangunan. Model matematik diterbitkan untuk TL tersebut dengan menjalankan pengujaan akustik yang tuju normal. Keputusan menunjukkan bahawa prestasi meningkat dengan ketara pada frekuensi yang susah semasa resonans jisim-udara-jisim berlaku di dalam sekatan padu lembar kembar  lazim. Ini penting terutamanya untuk sumber bunyi yang pradominan pada frekuensi rendah. Ia juga boleh dikawal dengan menalakan saiz dan jumlah lubang serta luang udara di antara panel-panel  tersebut.

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Published
2011-12-20
How to Cite
Ismail, A. Y. (2011). SOUND TRANSMISSION LOSS OF A DOUBLE-LEAF SOLID-MICROPERFORATED PARTITION UNDER NORMAL INCIDENCE OF ACOUSTIC LOADING. IIUM Engineering Journal, 12(3). https://doi.org/10.31436/iiumej.v12i3.164