scholarly journals Identification of uncertainty levels of acoustic properties of biocomposites under different mounting conditions in impedance tube tests

2021 ◽  
Vol 69 (5) ◽  
pp. 392-400
Author(s):  
Hasan Koruk ◽  
Yusuf Saygili ◽  
Garip Genc ◽  
Kenan Y. Sanliturk
Keyword(s):  
Sound Absorption ◽  
Transmission Loss ◽  
Acoustic Properties ◽  
Petroleum Jelly ◽  
Impedance Tube ◽  
Hard Materials ◽  
Inner Diameter ◽  
Acoustic Properties Of Materials ◽  
Impedance Tube Method ◽  
Textured Materials

Impedance tube method is widely used to measure acoustic properties of materials. Although this method yields reliable acoustic properties for soft textured materials, uncertainty levels of measured acoustic properties for hard materials, including biocomposites, can be quite large, mainly due to uncertain mounting conditions. Here, the effects of mounting conditions on the acoustic properties of biocomposites in an impedance tube are investigated. First, nominally identical biocomposite samples with a diameter equal to the inner diameter of impedance tube are manufactured and their acoustic properties are determined. As hard materials practically cause fitting problems in the impedance tube, the diameters of samples are reduced, as in practice, by small amounts and acoustic properties of modified samples are determined. Furthermore, in order to match the diameters of samples to the inner diameter of impedance tube, different materials such as tape, petroleum jelly and cotton are applied around samples to close the air gap between the samples and the tube's inner wall. All the results are compared, and the uncertainty levels caused by different mounting conditions on the acoustic properties of biocomposites are identified. The results show that the transmission loss (TL) measurements are dramatically affected by the mounting conditions while the sound absorption conditions are less sensitive to the mounting conditions. The deviations in the measured TL levels are highest for the samples with tape and wax (10–15 dB). On the other hand, the deviations in the measured sound absorption coefficients are highest for the samples with cotton and tape (1–2%).

scholarly journals Development of Impedance Tube to Measure Sound Absorption Coefficient

2019 ◽  
Vol 8 (6) ◽  
pp. 3218-3222
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Acoustic Property ◽  
Small Sample ◽  
Textile Material ◽  
Acoustic Properties ◽  
Sound Absorption Coefficient ◽  
Impedance Tube ◽  
Significant Difference

An acoustic property of textile material can be measured using an impedance tube, is the most popular technique to measure normal sound absorption and transmission loss. This method consuming less time and a very small sample is required to assess the acoustic properties of the materials. Unfortunately, the cost of the impedance tube and software used for measurement is very high. This paper gives information about how to develop a cost-effective impedance tube suitable for researchers. The design, development, and fabrication of the impedance tube suitable for different frequencies with technical details are present here. Information related to some software which can be used to measure sound absorption coefficient also provided. To validate the testing results obtained from custom-build impedance tube, same samples were tested on commercially available impedance tube at PSG College, Coimbatore. It was observed that both the instruments provide almost same results, no statistically significant difference found in results. Base on the results design of customized impedance tube recommends to student and researcher interested in measuring acoustic properties of textile material

scholarly journals Investigation of the Sound Absorption and Transmission Loss Performances of Green Homogenous and Hybrid Luffa and Jute Fiber Samples

2021 ◽  
Author(s):  
Ahmet C. Ozcan ◽  
Kenan Y. Sanliturk ◽  
Garip Genc ◽  
Hasan Koruk
Keyword(s):  
High Frequency ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Natural Fibers ◽  
Acoustic Properties ◽  
Jute Fiber ◽  
Transmission Losses ◽  
Hybrid Fiber ◽  
Practical Applications ◽  
Impedance Tube Method

In order to promote the use of natural fibers in noise and vibration applications, the properties of these structures should be fully identified. The sound absorption coefficients (SACs) and transmission losses (TLs) of green luffa fiber samples are thoroughly investigated and their acoustic performances are compared with the acoustic performances of green homogenous jute and hybrid jute/luffa fiber samples in this study. For this purpose, green homogenous luffa and jute fiber samples and their green hybrid fiber samples with different thicknesses (10, 20, 30, and 40 mm) are produced and their SACs and TLs are determined using the impedance tube method. First, the methods for the experimental identification of acoustic properties are presented and the variations in the measured acoustic properties are identified. After that, the effects of sample thickness on the acoustic performances of homogenous luffa as well as jute samples and their hybrid fiber samples as a function of frequency are explored. The thickness-dependent tendencies of the SACs and TLs of homogenous and hybrid luffa and jute fiber samples for low, medium and high frequency ranges are determined. Then, the acoustic performances of the homogenous and hybrid luffa and jute samples are compared and evaluated. The results and analyses for the acoustic properties of homogeneous luffa and jute fiber samples and their hybrid fiber samples for a variety of thicknesses and different frequencies presented here can be used to design homogenous as well as hybrid luffa and jute fiber structures in practical applications.

scholarly journals The Effects of Various Additive Components on the Sound Absorption Performances of Polyurethane Foams

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Shuming Chen ◽  
Yang Jiang ◽  
Jing Chen ◽  
Dengfeng Wang
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Polyurethane Foams ◽  
Acoustic Properties ◽  
Acoustic Absorption ◽  
Absorption Properties ◽  
Maximum Enhancement ◽  
Flexible Polyurethane ◽  
Pu Foams

Flexible polyurethane (PU) foams comprising various additive components were synthesized to improve their acoustic performances. The purpose of this study was to investigate the effects of various additive components of the PU foams on the resultant sound absorption, which was characterized by the impedance tube technique to obtain the incident sound absorption coefficient and transmission loss. The maximum enhancement in the acoustic properties of the foams was obtained by adding fluorine-dichloroethane (141b) and triethanolamine. The results showed that the acoustic absorption properties of the PU foams were improved by adding 141b and triethanolamine and depended on the amount of the water, 141b, and triethanolamine.

scholarly journals Acoustic Properties of Mixing Empty Fruit Bunch and Oil Palm Frond Natural Fibres

2019 ◽  
Vol 8 (4) ◽  
pp. 6347-6349
Keyword(s):  
Oil Palm ◽  
Sound Absorption ◽  
Natural Fibre ◽  
Natural Fibres ◽  
Acoustic Properties ◽  
Empty Fruit Bunch ◽  
Frequency Range ◽  
Oil Palm Frond ◽  
Impedance Tube Method ◽  
Palm Frond

Natural fibre is being studied and used as sound absorber for its promising acoustic properties. For instance, Germany have commercial plants that are producing sound absorbers from natural fibre. Natural fibre is eco-friendly and has no effect on human health. Besides that, the production cost of natural fibre is cheaper than synthetic fibre. This research reported the thickness effects on acoustic properties in different ratios of natural fibres of empty fruit bunch (EFB) and oil palm frond (OPF). Four different thickness of low density fibre board (LDF) have been fabricated (12 mm, 14 mm, 16 mm and 18 mm) in density of 120 kg/m3 . The Sound Absorption Coefficient (SAC) was tested by using the Impedance Tube Method (ITM) according to ASTM E1050-98 standards at frequency from 0 Hz to 6400 Hz. The results show the values of SAC for all samples increase with increasing in thickness from frequency range of 0 Hz – 4500 Hz. It is noteworthy that the LDF with thickness of 16 mm and 18 mm can be classified as Class A sound absorbing material according to sound absorption classes and possess the SAC values of 0.8 and above at a wider frequency range, which is 2500 Hz to 6400 Hz. The combination of EFP and OPF natural fibres has a very promising and excellent performance in acoustic properties.

scholarly journals Comparison of sound absorption characteristics measured by impedance tube method and ensemble averaging technique on porous clay bricks

2021 ◽  
Vol 42 (3) ◽  
pp. 154-157
Author(s):  
Siwat Lawanwadeekul ◽  
Reiji Tomiku ◽  
Noriko Okamoto ◽  
Toru Otsuru ◽  
Masahiro Masuda ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Ensemble Averaging ◽  
Impedance Tube ◽  
Averaging Technique ◽  
Clay Bricks ◽  
Impedance Tube Method ◽  
Absorption Characteristics

scholarly journals Acoustic Properties of 316L Stainless Steel Hollow Sphere Composites Fabricated by Pressure Casting

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1047
Author(s):  
Chunhe Wang ◽  
Fengchun Jiang ◽  
Shuaiqi Shao ◽  
Tianmiao Yu ◽  
Chunhuan Guo
Keyword(s):  
Absorption Coefficient ◽  
Hollow Sphere ◽  
Sound Absorption ◽  
Random Distribution ◽  
Transmission Loss ◽  
Acoustic Properties ◽  
Sound Absorption Coefficient ◽  
Pressure Casting ◽  
Sound Transmission Loss ◽  
At Resonance

In this study, we prepared metal hollow sphere composites (MHSCs) using metal hollow spheres (MHSs) by pressure casting under vacuum conditions, and investigated the acoustic properties. The density of the MHSCs was measured using the mass to volume ratio, the microstructure of the MHSCs was observed using a scanning electron microscope, and the acoustic properties of the MHSCs were tested using an impedance tube. The measured MHSCs showed that the densities of the MHSCs with the random distribution of MHSs with diameter ~3.28 mm (1.74 g/cm3 to 1.77 g/cm3) (MHSC-3.28) were nearly equal to that of the MHSCs with the random distribution of MHSs with diameter ~5.76 mm (1.74 g/cm3 to 1.76 g/cm3) (MHSC-5.76), and lower than that of the MHSCs with the layered structure of MHSs with diameter ~3.28 mm (1.93 g/cm3 to 1.97 g/cm3) (MHSC-LS). Microstructural observations confirmed that the interface region between the MHSs and matrix demonstrated a simple physical combination pattern with pores. The acoustic properties of the MHSCs showed that the sound absorption coefficient of MHSC-LS was lower than that of MHSC-3.28 and higher than that of MHSC-5.76 at off-resonance. The sound absorption coefficient peak value of MHSC-3.28 was higher than that of MHSC-LS, and lower than that of MHSC-5.76 at resonance. The sound transmission loss of MHSC-3.28 was lower than that of MHSC-5.76, which shows the rules are independent from the resonance. The sound transmission loss of MHSC-LS was higher than that of MHSC-5.76 at resonance, but lower than that of MHSC-3.28 at off-resonance. In addition, we discuss the propagation mechanism of the sound waves in the MHSC, which is mainly determined by the distribution of the MHSs in the MHSC.

Foliar Sound Absorption Capacities of Tree Leaves by Impedance Tube Method

2021 ◽  
pp. 1-7
Author(s):  
Payal Rane - Acharekar ◽  
Ambika Joshi ◽  
Nitesh Joshi
Keyword(s):  
Sound Absorption ◽  
Tree Leaves ◽  
Impedance Tube ◽  
Impedance Tube Method

Sound Absorption and Insulation Properties of a Polyurethane Foam Mixed with Electrospun Nylon-6 and Polyurethane Nanofibre Mats

2019 ◽  
Vol 19 (6) ◽  
pp. 3558-3563 ◽  
Author(s):  
Mira Park ◽  
Hyeon Ku Park ◽  
Hye Kyoung Shin ◽  
Dawon Kang ◽  
Bishweshwar Pant ◽  
...  
Keyword(s):  
Polyurethane Foam ◽  
Sound Absorption ◽  
Nylon 6 ◽  
Sound Insulation ◽  
Electrospinning Technique ◽  
Acoustic Characteristics ◽  
Impedance Tube ◽  
Textile Materials ◽  
Electrospun Nanofibres ◽  
Impedance Tube Method

In recent years, noise has become a serious hazard and can have permanent biological and psychological effects on humans and other organisms in nature. Textile materials are commonly used as absorbent acoustic materials for noise reduction. This work examines the use of electrospun nylon-6 and polyurethane nanofibres (PU NFs) to improve the sound absorption and sound insulation properties of polyurethane foam. In this work, nylon-6 and polyurethane nanofibres were prepared by an electrospinning technique and were glued to a polyurethane foam. The sound absorption coefficient of the materials was measured by the impedance tube method. An impedance tube was used to measure the sound absorption and airborne sound insulation. The results showed decreased sound absorption properties, whereas the sound insulation was highly enhanced when polyurethane/nanofibre hybrids were used, as compared to the pristine polyurethane foam. Furthermore, the sound insulation properties of polyurethane foam were highly enhanced when the foam was combined with nylon-6 NFs, compared with the polyurethane foam with PU NFs. Therefore, by investigating the acoustic characteristics of electrospun nylon-6 and PU nanofibres, we believe that this study can broaden the application of electrospun nanofibres for sound pollution control.

Incorporation of Nanofiber Layers in Nonwoven Materials for Improving Their Acoustic Properties

2013 ◽  
Vol 8 (4) ◽  
pp. 155892501300800 ◽  
Author(s):  
Amir Rabbi ◽  
Hossein Bahrambeygi ◽  
Ahmad Mousavi Shoushtari ◽  
Komeil Nasouri
Keyword(s):  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Wide Band ◽  
Acoustic Properties ◽  
Sound Insulation ◽  
Sound Transmission Loss ◽  
Factors Affecting ◽  
Nonwoven Materials ◽  
Field Noise

Due to numerous developments in most industries and the increase in the usage of massive and powerful machines in every field, noise has become an unavoidable part of mechanized life and has brought about serious health hazards. The main aim of this work was to investigate the usability of polyurethane and polyacrylonitrile nanofibers for improving sound insulation properties over a wide band of frequencies and reducing weight and thickness of conventional polyester and wool nonwovens. The effect of the number of nanofiber layers and associated surface densities on acoustic properties was investigated. Sound transmission loss and sound absorption analysis using the impedance tube method were carried out as the main factors affecting acoustic behavior of samples. The results show that incorporation of nanofiber layers in nonwoven materials can improve both sound absorption and sound transmission loss simultaneously, especially in mid and lower frequencies, which are difficult to detect by conventional materials.

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