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

Trial applications at gymnasiums of in-situ sound absorption measurement method by ensemble averaging technique

2021 ◽  
Vol 263 (2) ◽  
pp. 4532-4537
Author(s):  
Toru Otsuru ◽  
Reiji Tomiku ◽  
Noriko Okamoto ◽  
Siwat Lawanwadeekul
Keyword(s):  
Measurement Method ◽  
Sound Absorption ◽  
Glass Wool ◽  
Absorption Measurement ◽  
Ensemble Averaging ◽  
Averaging Technique ◽  
In Situ Conditions ◽  
Measurement Consistency ◽  
Absorption Characteristics

The authors have been published a series of papers on a measurement method for sound absorption characteristics of materials using ensemble averaging technique, i.e., EA method. The papers' results included measurement mechanisms, measurement uncertainty, and so on. Herein, to examine adaptability, especially in in-situ conditions, the EA method is applied to measure absorption characteristics of materials installed in two gymnasiums. A glass-wool panel with the dimension of 0.5 m by 0.5 m by 0.05 m and with the density of 32 kg m^-3 was brought around and measured to check the measurement consistency. Several measurements were conducted during badminton plays were undergoing. Measured sound absorption coefficients revealed that most results agree well with those measured in reverberation rooms. Certain improvement is necessary for the specimen brought to the in-situ measurement to keep the consistency. The inconsistency is considered to originate from unstable conditions between the specimen and floor.

Applying the ensemble averaging method with a pressure–velocity sensor to measure sound absorption characteristics of porous clay bricks

2020 ◽  
Vol 164 ◽  
pp. 107250
Author(s):  
Siwat Lawanwadeekul ◽  
Toru Otsuru ◽  
Reiji Tomiku ◽  
Hiroyasu Nishiguchi ◽  
Noriaki Sakamoto ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Averaging Method ◽  
Ensemble Averaging ◽  
Velocity Sensor ◽  
Clay Bricks ◽  
Absorption Characteristics

Sound Absorption Characteristics of Porous Steel Manufactured by Lost Carbonate Sintering

2009 ◽  
Vol 1188 ◽  
Author(s):  
Miao Lu ◽  
Carl Hopkins ◽  
Yuyuan Zhao ◽  
Gary Seiffert
Keyword(s):  
Absorption Coefficient ◽  
Pore Size ◽  
Sound Absorption ◽  
Single Layer ◽  
Normal Incidence ◽  
Sound Absorption Coefficient ◽  
Absorption Coefficients ◽  
Impedance Tube ◽  
Absorption Characteristics

AbstractThis paper investigates the sound absorption characteristics of porous steel samples manufactured by Lost Carbonate Sintering. Measurements of the normal incidence sound absorption coefficient were made using an impedance tube for single-layer porous steel discs and assemblies comprising four layers of porous steel discs. The sound absorption coefficient was found not to vary significantly with pore size in the range of 250-1500 μm. In general, the absorption coefficient increases with increasing frequency and increasing thickness, and peaks at specific frequencies depending on the porosity. An increase in porosity tends to increase the frequency at which the sound absorption coefficient reaches this peak. An advantage was found in using an assembly of samples with gradient porosities of 75%-70%-65%-60% as it gave higher and more uniform sound absorption coefficients than an assembly with porosities of 75%.

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%).

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.

scholarly journals A Pilot Study on the Sound Absorption Characteristics of Chicken Feathers as an Alternative Sustainable Acoustical Material

2019 ◽  
Vol 11 (5) ◽  
pp. 1476 ◽  
Author(s):  
Asniawaty Kusno ◽  
Kimihiro Sakagami ◽  
Takeshi Okuzono ◽  
Masahiro Toyoda ◽  
Toru Otsuru ◽  
...  
Keyword(s):  
Pilot Study ◽  
Sound Absorption ◽  
Prediction Method ◽  
Fibrous Materials ◽  
Absorption Coefficients ◽  
Chicken Feathers ◽  
Absorption Performance ◽  
Flow Resistivity ◽  
Impedance Tube Method ◽  
Absorption Characteristics

This communication reports the results of a pilot study on the sound absorption characteristics of chicken feathers (CFs). Recently, demands for natural and sustainable materials have been extensively studied for acoustical purposes. CF has long been left wasted, however, they can be used for sound-absorbing purposes to improve acoustical environments as a sustainable and green acoustical material. In order to clarify their feasibility, samples of CF absorbers of various densities and thicknesses were prepared, and their sound absorption coefficients were measured by the standard impedance tube method. The measured results were also compared with those of conventional glass wools of the same densities and thicknesses. The results show that CFs have potentially good sound-absorption performance, which is similar to typical fibrous materials: increasing with frequency. Results of direct comparison with glass wool demonstrate that the absorption coefficients of CFs are comparable and, at some frequencies, somewhat higher than conventional glass wools in some cases. Additionally, the first step for searching a prediction method for the sound absorption performance of CFs, their flow resistivity was measured and a Delany–Bazley–Miki model was examined. However, the resultant flow resistivity was unexpectedly low, and the model gave only a much lower value than that measured. The reason for the discrepancies is the subject of a future study.

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