scholarly journals A Study on the Acoustic Absorption Performance of a Helmholtz Resonator

2008 ◽  
Vol 18 (1) ◽  
pp. 71-79 ◽  
Keyword(s):  
Helmholtz Resonator ◽  
Acoustic Absorption ◽  
Absorption Performance

scholarly journals Effect of Thickness and Perforation Size on the Acoustic Absorption Performance of a Micro-Perforated Panel

2021 ◽  
Vol 335 ◽  
pp. 03016
Author(s):  
Yi-San Wong ◽  
Vignesh Sekar ◽  
Se Yong Eh Noum ◽  
Sivakumar Sivanesan
Keyword(s):  
Absorption Coefficient ◽  
Urban Areas ◽  
Sound Absorption ◽  
Rapid Development ◽  
Noise Pollution ◽  
Sound Absorption Coefficient ◽  
Sound Insulation ◽  
Acoustic Absorption ◽  
Psychological Disturbance ◽  
Absorption Performance

In current times, noise pollution is especially apparent in urban areas due to rapid development in transportation, industrialization, and urbanization. The worsening noise pollution is detrimental to human health and behaviour as it can contribute to disorders and psychological disturbance. Thus, noise regulation is crucial and must be addressed with immediate effect. Micro-perforated panels (MPP) can be a potential solution to mitigate noise on a commercial scale. Researchers have addressed the mechanics behind the enhancement of acoustic absorption through micro-perforation and some suggestions have been made, such as the effect of structural variation on sound absorption performance. Hence, this research aims at optimizing the sound absorption performance of an MPP by determining the connection between thickness and perforation size with sound absorption coefficient. Three cases were considered: (i) varying perforation size, (ii) varying thickness, and (iii) varying perforation size and thickness simultaneously. Based on the Maa prediction model, the sound absorption performance for all three cases have been simulated through the MATLAB software. Results show that the increase in both thickness and perforation size together increases the peak value of sound absorption coefficient (SAC). It also shifts the peak towards the higher frequency region and narrows the bandwidth. The findings of this study indicate the potential of thick MPPs as commercial sound absorbers by adjusting the size of perforations. Thicker and sturdier MPPs with optimal acoustic resistance and reactance can act as reliable sound absorbers for sound insulation purposes.

Sound Absorption Performance of Micro-Perforated Panel (MPP) Made from Biodegradable Composite (Hibiscus Cannabinus+PLA) Material

2018 ◽  
Vol 791 ◽  
pp. 3-9
Author(s):  
Desmond Daniel Vui Sheng Chin ◽  
Musli Nizam Bin Yahya ◽  
Nazli Bin Che Din ◽  
Pauline Ong ◽  
Izzuddin Bin Zaman ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Helmholtz Resonator ◽  
Hibiscus Cannabinus ◽  
Absorption Properties ◽  
Promising Alternative ◽  
Metallic Material ◽  
Biodegradable Composite ◽  
Kenaf Fibre ◽  
Peak Absorption ◽  
Absorption Performance

Micro-perforated panel (MPP) has been widely considered as a very promising alternative in absorbing sound by utilizing the concept and mechanism of Helmholtz resonator. Most of the existing MPP are made of metallic material such as aluminium or stainless steel. In this study, biodegradable composite micro-perforated panel (BC-MPP) made from kenaf fibre and polylactic acid (PLA) will be implemented. Impedance tube test shows that BC-MPP possessed excellent sound absorption properties and could rival with conventional MPP. The peak absorption of BC-MPP is also more significant compare to conventional MPP as the peak absorption almost reaches unity.

scholarly journals Reducing Railway Noise with Porous Sound-Absorbing Concrete Slabs

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Caiyou Zhao ◽  
Ping Wang ◽  
Li Wang ◽  
Dan Liu
Keyword(s):  
Noise Reduction ◽  
Concrete Slabs ◽  
Acoustic Absorption ◽  
Absorption Properties ◽  
Aggregate Gradation ◽  
Porous Concrete ◽  
Railway Noise ◽  
Laboratory Results ◽  
Absorption Performance ◽  
Concrete Materials

The effect of porous sound-absorbing concrete slabs on railway noise reduction is examined in this paper. First, the acoustical absorption coefficients of porous concrete materials with various aggregate types, gradations, fibre contents, and compaction indexes are measured in the laboratory. The laboratory results show that porous concrete that uses a composite of expanded perlite and slag as aggregate can not only obtain good acoustical absorption properties but also satisfy mechanical requirements. Also, the gradation of the combined aggregate has a significant effect on the acoustic absorption performance of the porous concrete, with an optimal aggregate gradation of 1~3 mm. Furthermore, the fibre content and compaction index affect both the strength and the acoustic absorption property of the porous concrete, with the optimum value of 0.3% and 1.6, respectively. Then, the findings from the laboratory studies are used to make porous sound-absorbing concrete slabs, which are applied in a test section. The measurements indicate that porous sound-absorbing concrete slabs can significantly reduce railway noise at different train speeds and that the amount of the noise reduction changes roughly linearly with speed when the train is traveling at less than 200 km/h. The maximum noise reduction is 4.05 dB at a speed of 200 km/h.

Acoustic absorption performance of polyacrylic composite latex

1995 ◽  
Vol 58 (3) ◽  
pp. 565-569 ◽  
Author(s):  
Kangde Yao ◽  
Guoxiang Cheng ◽  
Tao Lu ◽  
Wengsheng Zhu ◽  
Qingchi Shun ◽  
...  
Keyword(s):  
Acoustic Absorption ◽  
Absorption Performance

Novel implementation of natural fibro-granular materials as acoustic absorbers

2018 ◽  
Vol 49 (9-10) ◽  
pp. 311-316 ◽  
Author(s):  
Hasina Mamtaz ◽  
Mohammad Hosseini Fouladi ◽  
Satesh Narayana Namasivayam ◽  
Saadman H Sayed ◽  
Tahani H Sayed ◽  
...  
Keyword(s):  
Granular Materials ◽  
Significant Contribution ◽  
Low Frequency ◽  
Frequency Region ◽  
Acoustic Absorption ◽  
Granular Composite ◽  
Absorption Performance ◽  
Predicted Values ◽  
Analytical Tools ◽  
Good Agreement

In this study, a new innovative fibro-granular composite was prepared as a natural acoustic material by combining fibrous and granular materials. Delany–Bazley model and Biot–Allard techniques were utilized to estimate the absorption coefficient of the developed composite material. The predicted values were validated through an analytical outcome employing Johnson–Champoux–Allard technique and an experimentally measured value which were conducted in an impedance tube. The outcomes showed the reflection of the good agreement between the analytical and experimental methods. The current research concluded that the introduction of granular materials provides significant contribution in enhancing the surface area within the composite, thereby achieving a promising acoustic absorption in the low-frequency region which is below 1 kHz. In addition, the current research also reports that, like Johnson–Champoux–Allard model, Delany–Bazley and Biot–Allard models are also two efficient analytical tools for predicting the significant low-frequency acoustic absorption performance of a fibro-granular composite.

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