Sound absorption of textile curtains – theoretical models and validations by experiments and simulations

2016 ◽  
Vol 88 (1) ◽  
pp. 36-48 ◽  
Author(s):  
Reto Pieren ◽  
Beat Schäffer ◽  
Stefan Schoenwald ◽  
Kurt Eggenschwiler
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Planning Process ◽  
Measurement Data ◽  
Theoretical Models ◽  
Sound Absorption Coefficient ◽  
Absorption Coefficients ◽  
Semi Empirical ◽  
Field Sound ◽  
Good Agreement

Textile curtains can be designed to be good sound absorbers. Their acoustical performance, as usually described by the sound absorption coefficient, not only depends on the textile itself but also on the drapery fullness and the backing condition, that is, the spacing between the fabric and a rigid backing wall, or the absence of a backing in the case of a freely hanging curtain. This article reviews existing models to predict the diffuse-field sound absorption coefficient, which to date can only predict the case of flat curtains. A set of existing models is extended to the case of curtains with drapery fullness using a semi-empirical approach. The models consider different backing conditions, including freely hanging curtains. The existing and new models are validated by comparing predicted sound absorption coefficients with data measured in a reverberation room. Hereby, curtains consisting of different fabrics and with different degrees of fullness are considered. Besides situations with rigid backing, also the measurement data of textiles hung freely in space are included in this study. Comparisons reveal a very good agreement between measured and predicted sound absorption coefficients. Compared to currently available commercial sound absorption prediction software that can only handle the situation of flat textiles with rigid backing, the results of the presented models not only show a better agreement with measured data, but also cover a broader range of situations. The presented models are thus well applicable in the design and development of new textiles as well as in the room acoustical planning process.

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 Sound Absorption Coefficient of Different Green Materials Polymer on Noise Reduction

2020 ◽  
Vol 9 (3) ◽  
pp. 2773-2777
Keyword(s):  
Absorption Coefficient ◽  
Noise Reduction ◽  
Sound Absorption ◽  
New Technologies ◽  
Raw Materials ◽  
Agricultural Waste ◽  
Noise Pollution ◽  
Sound Absorption Coefficient ◽  
Absorption Coefficients ◽  
Green Materials

One of the sources of noise pollution to environment is from the consumption of electrical and mechanical appliances usage at home and industries. Growth development and advancement of heavy equipment in construction work further emphasize the necessity used of new technologies for noise reduction. The best technique of control or reducing of noise is by using the materials that can absorb the noise by materials itself. Potential materials from agricultural waste as sound absorber were identified. There are two main objectives in this study; First is to produce acoustic absorber by using natural materials. Second is to identify their sound absorption coefficients. The samples were fabricated using the raw materials from banana stem, grass, palm oil leaves and lemongrass mixed with binding agents of polyurethane and hardener to the ratio of 1:4. The diameters of the samples consist of 28mm and 100mm and the thickness is 10mm. The samples sound absorption coefficients were measured according to standards ASTM E1050-98 / ISO 105342-2 (Impedance tube method). Sound absorption coefficient of the materials depends on frequencies choose. The frequencies values used in this study were in the range from 500Hz to 4500Hz. Material made from grass have a higher average sound absorption coefficient value which is 0.553. All tested samples also can be categories under class D type of materials based on sound absorption coefficient value.

scholarly journals AKYTOJO BETONO GARSO ABSORBCIJOS TYRIMAI/POROUS CONCRETE SOUND ABSORPTION INVESTIGATION

1996 ◽  
Vol 2 (8) ◽  
pp. 67-72
Author(s):  
Antanas Laukaitis ◽  
Vytautas Lasauskas
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Concrete Slab ◽  
Wave Resistance ◽  
Sound Absorption Coefficient ◽  
Wave Parameter ◽  
Concrete Slabs ◽  
Uniform Density ◽  
Absorption Coefficients ◽  
Porous Concrete

Low-density porous concrete can be used as a sound absorbing material. This paper generalizes porous concrete sound absorption investigations. Porous concrete relative wave resistance modulus is longer than air wave resistance W=1 and that is why this material can be ascribed to materials with a high resistance to air flows, i.e. materials with a satisfactory sound absorption. Various thickness porous concrete sample sound absorption coefficients can be calculated according to equations (1), (2), (3), when wave parameter values are determinated (Table 1). Normal sound absorption coefficient measurement results (Fig. 1) show that for 35 mm and thicker samples the coefficient does not vary. It means that the samples apparent resistance (impleance) coincides with the materials wave resistance. The sound absorption coefficient increases (Fig. 2) with a decrease in porous concrete density. The asymmetric average dependency is expressed by a rectilinear curve (Fig. 3). The sound absorption coefficient depends not only on porous concrete density, but also on its nature (Fig. 4). The different sound absorption coefficient values for uniform density porous concrete can be explained by the various structure of porous concrete products, i.e. a change in pore dimensions, their amount and distribution (Fig. 5, Table 2). The production of acoustical slabs has shown that 280350 kg/m3 density porous concrete products are not sufficiently strong. It was therefore decided to increase their density to 460 kg/m3, with the purpose of increasing the sound absorption coefficient by using various special form resonators (cavity-type accelerators). The influence of the cuts on sound absorption is given in Fig. 6 (cut step is 22 mm). Measurements in a reverberation chamber have shown that the sound absorption coefficient value in porous concrete slabs with deeper or complex cuts increases, but it is harder to produce slabs with complex form cuts. It is easier to make a simple form resonator. Reverberated sound absorption for regular form resonators is given in Fig. 7. Porous concrete slab surface acoustical resistance decreases due to cuts and that is why there is an increase in sound absorption coefficients (Fig. 7, 2 and 3 curves).Porous concrete slabs with resonator cuts on both sides can be used in spacious constructions, for noise absorption in industrial premises. In this case, the construction sound absorption coefficient depends on the lay-out of these slabs. Three types of special lay-outs were investigated (Fig. 8, Table 3). Most of the investigated constructions have revertible sound absorption coefficients higher than 1. This is explained by sound diffraction phenomena on the slab edges. The most effective of all the investigated constructions are those where porous concrete slabs with two-sided perforations are hung jointly (Fig. 8, curves 6 and 10). They are effective in the entire distance between the slabs. The reverberation absorption coefficient decreases for all types of constructions (Fig. 8, curves 1 and 2, 5 and 6, 7–10). The special construction sound absorption coefficient can be changed by selecting porous concrete slab lay-out.

The Semi-Empirical and Empirical Models for Predicting Sound Absorption Coefficients for a Novel Porous Laminated Composite Material

2003 ◽  
Vol 9 (11) ◽  
pp. 1249-1263
Author(s):  
Tsung-Lung Yang ◽  
Rongshun Chen
Keyword(s):  
Composite Material ◽  
Absorption Coefficient ◽  
Empirical Model ◽  
Sound Absorption ◽  
Laminated Composite ◽  
Sound Absorption Coefficient ◽  
Numerical Predictions ◽  
Viscous Loss ◽  
Semi Empirical ◽  
Laminated Composite Material

Made of polymer, metal, and polymer fibers of low melting point, a porous laminated composite material (PLCM) exhibits very highly sound absorption coefficient over the frequency of 500-2000 Hz with a relatively thin structure. In this paper we present two models to predict sound absorption characteristics for a PLCM. Firstly, we derive a semi-empirical model in which the flow resistivity of the PLCM is a function of the fibrous surface area under the assumption that most energy loss is due to the viscous loss consumed in the fibrous surface of a PLCM. Secondly, we propose an empirical model to predict the characteristic impedance and the propagation constant, which then is employed to determine the sound absorption coefficient for a new PLCM. Numerical predictions have been performed and experiments have been conducted to validate the two proposed models.

scholarly journals ESTIMATING SOUND ABSORPTION IN COEFFICIENT OF PRAYERS IN MOSCQUES

Akustika ◽  
2019 ◽  
Vol 32 ◽  
pp. 227-230
Author(s):  
Vasily Aleshkin ◽  
Christofor Schirjetsky ◽  
Anton Subbotkin
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Strong Influence ◽  
Calculated Data ◽  
Absorption Measurement ◽  
Sound Absorption Coefficient ◽  
Absorption Coefficients

The article deals with analysing sound absorption of prayers in big congregational mosques. Peculiarity of sound absorption measurement in prayer halls is linked with the capability of mosque worshipers to pray in different poses with diverse arrangements as opposed to the traditional halls where people usually sit in chairs. This factor has a strong influence over the sound absorption coefficient which should be taken into account in acoustical design of such buildings. Within the framework of this study sound absorption coefficients (SAC) were measured using reverberation room method for people praying on carpets in different poses. Calculated data have been

scholarly journals Koefisien Serap Bunyi Papan Partikel Dari Bahan Serbuk Kayu Kelapa

Jurnal MIPA ◽  
2013 ◽  
Vol 2 (1) ◽  
pp. 56
Author(s):  
Thamrin Suhaemi ◽  
Seni H. J. Tongkukut ◽  
As'ari .
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Base Material ◽  
Sample Thickness ◽  
Sound Absorption Coefficient ◽  
Wood Dust ◽  
Particle Board ◽  
Absorption Coefficients ◽  
Board Thickness

Telah dilakukan penelitian untuk mengetahui karakteristik koefisien serap bunyi papan partikel dari bahan dasar serbuk kayu kelapa. Papan partikel dibuat dengan mencampur serbuk kayu kelapa dengan tepung kanji, dicetak, dan dikeringkan. Sampel berbentuk silinder, dibuat sebanyak 4 buah dengan tebal : (1,15 cm), (1,95 cm), (2,95 cm) dan (4,05 cm). Nilai koefisien serap bunyi sampel diukur menggunakan alat ukur koefisien serap bunyi. Hasil penelitian menunjukkan, ketebalan sampel mempengaruhi nilai koefisien serap bunyi (α) yaitu pada frekuensi 600 Hz. Koefisien serap bunyi (α) semakin menurun dengan bertambahnya ketebalan papan partikel (sampel penyerap).The research had been doing to know characteristic sound absorption coefficient of particle board which made from base material coconut wood dust. The particle board made by mix of coconut wood dust with cornstarch then pressed and dried. The particle board as a sample is cylinder with diameter 8,5 cm. The thick of four samples are 1,15 cm, 1,95 cm, 2,95 cm, and 4,15 cm. The sound absorption coefficient have measured by sound absorption coefficient instruments. The result is sample thickness has influence to sound absorption coefficient values such as at 600 Hz frequencies. Sound absorption coefficients is decreasing to the increasing of the particle board thickness (absorber sample).

scholarly journals Optimization of Shunted Loudspeaker for Sound Absorption by Fully Exhaustive and Backtracking Algorithm

2021 ◽  
Vol 11 (12) ◽  
pp. 5574
Author(s):  
Zihao Li ◽  
Xin Li ◽  
Bilong Liu
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Moving Mass ◽  
Frequency Range ◽  
Force Factor ◽  
Coil Inductance ◽  
Specific Frequency ◽  
Circuit Resistance ◽  
Good Agreement

The shunted loudspeaker with a negative impedance converter is a physical system with multiple influencing parameters. In this paper, a fully exhaustive backtracking algorithm was used to optimize these parameters, such as moving mass, total stiffness, damping, coil inductance, force factor, circuit resistance, inductance and capacitance, in order to obtain the best sound absorption in a specific frequency range. Taking the maximum average sound absorption coefficient in the range of 100–450 Hz as the objective function, the optimized parameters of the shunted loudspeaker were analyzed. Simulation results indicated that the force factor and moving mass can be sufficiently reduced in comparison with that of a typical four-inch loudspeaker available on the market. For a given loudspeaker from the market as an example, the four optimized parameters of the shunted loudspeaker were given, and the sound absorption coefficient was measured for verification. The measured results were in good agreement with the predicted results, demonstrating the applicability of the algorithm.

scholarly journals Acoustic Panels Made of Paper Sludge and Clay Composites

2021 ◽  
Vol 13 (2) ◽  
pp. 637
Author(s):  
Tomas Astrauskas ◽  
Tomas Januševičius ◽  
Raimondas Grubliauskas
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Composite Panel ◽  
Sound Absorption Coefficient ◽  
Core Material ◽  
Paper Sludge ◽  
Frequency Range ◽  
Absorption Properties ◽  
Air Gaps ◽  
The Core

Studies on recycled materials emerged during recent years. This paper investigates samples’ sound absorption properties for panels fabricated of a mixture of paper sludge (PS) and clay mixture. PS was the core material. The sound absorption was measured. We also consider the influence of an air gap between panels and rigid backing. Different air gaps (50, 100, 150, 200 mm) simulate existing acoustic panel systems. Finally, the PS and clay composite panel sound absorption coefficients are compared to those for a typical commercial absorptive ceiling panel. The average sound absorption coefficient of PS-clay composite panels (αavg. in the frequency range from 250 to 1600 Hz) was up to 0.55. The resulting average sound absorption coefficient of panels made of recycled (but unfinished) materials is even somewhat higher than for the finished commercial (finished) acoustic panel (αavg. = 0.51).

scholarly journals Air permeability and sound absorption coefficient changes from ultrasonic treatment in a cross section of Malas (Homalium foetidum)

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Chun-Won Kang ◽  
Eun-Suk Jang ◽  
Nam-Ho Lee ◽  
Sang-Sik Jang ◽  
Min Lee
Keyword(s):  
Absorption Coefficient ◽  
Ultrasonic Treatment ◽  
Sound Absorption ◽  
Gas Permeability ◽  
Treated Wood ◽  
Untreated Wood ◽  
Sound Absorption Coefficient ◽  
Permeability Constant ◽  
Average Value ◽  
Permeability Increase

AbstractWe investigated the effect of ultrasonic treatment on Malas (Homalium foetidum) gas permeability and sound absorption coefficient using the transfer function method. Results showed a longitudinal average Darcy permeability constant of 2.02 (standard deviation SD 0.72) for untreated wood and 6.15 (SD 3.07) for ultrasound-treated wood, a permeability increase of 3.04 times. We also determined the average sound absorption coefficients in the range of 50 to 6.4 kHz and NRC (noise reduction coefficient: average value of sound absorption coefficient value at 250, 500, 1000, and 2000 Hz) of untreated Malas. Those values were 0.23 (SD 0.02) and 0.13 (SD 0.01), respectively, while those of ultrasonic-treated Malas were 0.28 (SD 0.02) and 0.14 (SD 0.02), a 19.74% increase in average sound absorption coefficient.

Research of Possibilities of Using the Recycled Materials Based on Rubber and Textiles Combined with Vermiculite Material in the Area of ​​Noise Reduction

2014 ◽  
Vol 1001 ◽  
pp. 171-176 ◽  
Author(s):  
Pavol Liptai ◽  
Marek Moravec ◽  
Miroslav Badida
Keyword(s):  
Absorption Coefficient ◽  
Standing Wave ◽  
Sound Pressure Level ◽  
Sound Absorption ◽  
Sound Pressure ◽  
Sound Level ◽  
Pressure Level ◽  
Sound Absorption Coefficient ◽  
Physical Parameters ◽  
Materials Research

This paper describes possibilities in the use of recycled rubber granules and textile materials combined with vermiculite panel. The aim of the research is the application of materials that will be absorbing or reflecting sound energy. This objective is based on fundamental physical principles of materials research and acoustics. Method of measurement of sound absorption coefficient is based on the principle of standing wave in the impedance tube. With a sound level meter is measured maximum and minimum sound pressure level of standing wave. From the maximum and minimum sound pressure level of standing wave is calculated sound absorption coefficient αn, which can take values from 0 to 1. Determination of the sound absorption coefficient has been set in 1/3 octave band and in the frequency range from 50 Hz to 2000 Hz. In conclusion are proposed possibilities of application of these materials in terms of their mechanical and physical parameters.

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