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Measurement setup for the normal incidence sound absorption coefficient of thin fabrics (two-microphone impedance tube).
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A theoretical model for the oblique incidence sound absorption coefficient of thin woven fabrics backed by an air cavity is presented where the fabric is acoustically described by its specific airflow resistance and its surface mass density. The theoretical model is illustrated by an equivalent electrical circuit and validated in the case of normal...
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Context 1
... incidence absorption coefficients of fabrics were measured according to the standard ISO 10534- 2, 24 using a Bruël & Kjaer two-microphone impedance tube of type 4206, as illustrated in Figure 4. The tube had a diameter of 10 cm allowing measurements in the range from 100 Hz to 1.75 kHz with a frequency reso- lution of 5 Hz. ...
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Citations
... Recently, several models were developed to simulate the attenuation of acoustic waves. For instance, Pieren's model is related to airflow resistivity, areal density and the distance of the backing air gap [5,6]. ...
... According to reported studies [10,11], tortuosity is closely related to the position of the quarter-wavelength peaks and also determines the sound absorption behavior at the high frequency of porous materials. Therefore, these models could not well describe the minimum absorption valley value of sound absorption curves at a high-frequency range [5,6,12]. ...
... As shown in Figure. 1 (a), the resonant sound absorber system includes a membrane-like layer and a backed air gap with the distance of D. The weaving structure of the woven fabric is shown in Figure. 1 (b), where a is length and b is the width of perforated rectangularly shaped patulous pores. In the previous work of Pieren [5], a model is established to predict the noise reduction of textile gap through an equivalent circuit method. As for the fabric, the surface impedance ZT can be calculated by: ...
The fabric has been widely used as a noise-reduction material. This paper presents a revised equivalent circuit model to simulate the acoustical behavior of woven fabric with backing an air gap, with a special focus on including a tortuosity parameter. The simulated sound absorption of three fabrics with and without the tortuosity parameter was experimentally validated. The equivalent circuit model including the tortuosity parameter predicts the absorption curve better, particularly at the local minima in comparison to the existing models without the tortuosity effects. It is beneficial to the structural design of woven fabric with enhanced sound absorption.
... Accurate measurement of sound absorption is crucial for selecting proper components and design structures for acoustic materials. A considerable amount of literature has been published on the sound absorption of textile materials [7][8][9][10]. These studies have focused on sound absorption measurement in of textile materials [6,[11][12][13], as well as the model establishment and sound absorption prediction [14][15][16][17][18]. Various composite materials composed of fabric and textile fiber show good sound absorption performance [10,19]. ...
Textile materials have demonstrated significant potential in sound noise reduction due to their porous, lightweight, and easily processed nature. However, the current experimental setup for measuring the sound absorption of small-sized samples is expensive. Additionally, there is a lack of suitable equipment for measuring the sound absorption of flexible textiles as it is challenging to mount flexible samples into an impedance tube. This paper presents the design, fabrication, and testing of impedance tubes specifically designed for measuring the sound absorption coefficients of textile materials. The impedance tubes were designed based on the transfer function and two-microphone methods, with diameters of 100 mm and 30 mm. These tubes covered frequency ranges from 200-1600 Hz and 500-6400 Hz, respectively. Furthermore, improved sample holders were developed to mount flexible textile materials without altering the acoustic impedance characteristics of the front surface of the test sample. Validation experiments were conducted on melamine foams, and the results were compared with those obtained from the commercial B&K 4206 setup. The results obtained from the designed setup showed good agreement with those from the B&K 4206 system. The maximum error observed was 8% at 2800 Hz for the 30 mm diameter tube and 8.3% at 1600 Hz for the 100 mm diameter tube. Finally, the designed system was used to measure the sound absorption coefficients of textile materials with varying densities. The results obtained were consistent with the material properties, demonstrating the effectiveness of the designed setup.
... Natural fibers such as jute, hemp, and flax yarns are preferred because of their biodegradability and superior sound-absorbing qualities (Ahirwar and Behera, 2022b;Rani et al., 2020). Pieren et al. (Pieren, 2012;Pieren and Heutschi, 2015) developed a model for predicting the impedance of a thin fabric using an equivalent electrical circuit method and successfully validated it. Elkhateeb et al. (2016;Advanced Functional Textiles and Polymers., n.d.) investigated the sound absorption properties of carpets made from acrylic, polypropylene, and woolen yarn using the reverberation chamber methodology. ...
The ability of composites to insulate against noise and heat is crucial when utilized in buildings and other public structures and provide enhanced load bearing properties. Three-dimensional (3D) woven textile structural fabric and composites are one of the least investigated. Therefore, in this research, the acoustic behavior of various woven structures was investigated. The effect of weave geometry, weave architecture, number of stuffer layers, etc. on the acoustic behaviors of 3D woven orthogonal fabrics was studied. The textile reinforced composites were also characterized for tensile properties. The acoustic performance of the woven fabrics also depends on the air porosity in the structure. Therefore, investigation of air flow resistance and its correlation with sound absorption coefficient is very essential. It was observed that the acoustic behavior of jute and flax orthogonal fabrics is superior to glass fabrics. Fiber-reinforced composites show less sound absorption characteristics due to the infusion of epoxy resin.
... Woven fabric is formed with two types of porosity, where the micro-porosity is created by the gap between fibers in the yarn and macroporosity is formed between the yarn strands (Kang et al., 2019;Samuel et al., 2021). The correlation of texture of woven textiles and sound adsorption was further investigated, and sound absorption model was also established (Cai et al., 2020;Iwan et al., 2023;Li et al., 2020;Pieren, 2012). The intrinsic characteristics of the fiber type can also determine the sound absorption, and the sound absorption is enhanced by a lower yarn linear density and finer yarns (Barburski et al., 2019;Witczak et al., 2021;Yang et al., 2020). ...
... [44]. • Auralisation of environmental noise [45] such as from wind turbines [46][47], road traffic [48] [49] and aircrafts [50][51] • And finally, last but not least, in the field of materials science, Empa's core area: the development of materials and measurement as well as characterisation methods for acoustic materials in buildings [52]- [55], and the promising development of metamaterials like phononic crystals [56]- [58]. ...
A brief history of acoustics at the Swiss Federal Institute of
Technology (ETH) in Zurich and at the Swiss Federal Laboratories
for Materials Science and Technology (Empa) in
Dübendorf is presented, focusing on the period between
1920-1970. A first acoustics laboratory was set up by lecturer
Franz Max Osswald at the ETH in the 1920s. The work was
continued by Prof. Willi Furrer who, together with Prof. Anselm
Lauber, wrote a standard work on acoustics. Both authors
were associate professors at ETH. However, it was
never possible to establish a dedicated chair or institute for
acoustics despite the status of the prestigious technical university.
Early on, at a meeting in September 1944, the ETH
management stated that no separate chair should be established
for acoustics because it "eludes scientific research,
since it deals mainly with questions of practical application
and empiricism". Since then, lectures on acoustics have been
held regularly at various faculties of ETH and some research
projects have been carried out with remarkable results. However,
in 1962 a laboratory for acoustics and noise control was
founded at Empa, which is part of the ETH Domain, and is
today a recognised laboratory with considerable scientific
output.
... Alternatively, several researchers have used woven fabric to realize the MPP absorber, such as micro-perforation back by mesh [20] and the cotton yarn with facile dip-coating method [21,22]. In contrast, others focused on modelling and numerical calculations for woven absorptions, such as Pieren [23][24][25], Prasetiyo et al. [26,27], and Onen and Caliskan [28]. Meanwhile, Desendra et al. [29] conducted early investigation on the sound absorption characteristics of commercial woven fabrics under MPP configuration by performing a series of sound absorption measurements.. ...
Woven fabric perforation is helpful to be adopted to meet the microstructure requirement of a micro-perforated panel (MPP) absorber. Unlike conventional MPP, the woven fabric micro-perforations are formed by yarn in the x (weft) and y (warp)-directions. Hence, minute holes of the MPP with a diameter of 0.1–0.3 mm or a high perforation ratio are expected to be easily fabricated, while such a specification is difficult to realize on a solid surface, as found in some studies. The study presented here focuses on the use of minute holes in MPP absorbers by woven fabrics and discusses the minute hole properties of woven fabrics and their associated absorption characteristics. Theoretical results by Maa’s model are also used to validate resulting characteristics found from the experimental investigations. It is found that minute holes with around 0.10–0.20 mm diameter have been successfully fabricated by controlling weft yarn density. The woven fabrics are capable of producing half-absorption bandwidth of up to 5000 Hz (>3 octaves), while the peak of the absorption coefficient can be more than 0.8. In addition, varying hole diameter with the order of 10−2 mm can change the absorption behavior for both peak absorption and absorption bandwidth. Such behavior is confirmed by comparing the results with the theoretical model. This study also indicates that Maa’s model is still applicable for predicting absorption of MPP developed based on woven fabric material.
... Dias et al. (Dias & Monaragala, 2006) have geometrically simulated plain knitted fabric as a porous layer with distributed cylindrical pores perpendicular to the incident surface, which can be modelled as uniform circular cylinders in analyzing the energy attenuation of acoustic waves. A theoretical model was also proposed for characterizing the acoustical behavior of thin fabric with backing air gap, and the simulation process is based on airflow resistivity and specific areal weight (Pieren, 2012). The optimization of airflow resistivity and air cavity distance can simultaneously determine the acoustic performance of double-layered woven fabric absorber (Prasetiyo et al., 2020). ...
... Similar with the above-mentioned impedance Z f of sound-induced vibration effects, Z m ¼ jxm indicates the inductance of inductor. The surface impedance is corresponding to the parallel connection of impedance R s and Z m , as follows (Pieren, 2012): ...
The main aim of this work is to investigate the acoustical properties of cross-stitched fabric, which exhibits a similar structure with micro-perforated plate. The sound absorption coefficients of cross-stitched fabric with different specifications were measured, where the backing air cavity distance is 1 cm, 2 cm, and 3 cm, respectively. These distances are suitable to the practical interior decoration applications of cross-stitched fabric painting. Cross-stitched fabric can be made into diversity of artistic patterns through manual or mechanized embroidery technology. This work has also studied the effects of multifarious embroidered patterns on the sound absorption coefficients of fabrics with different backing air cavity distance. Classical micro-perforated model, vibrational micro-perforated model, and airflow resistance based model were used to predict the sound absorption of cross-stitched fabric. In summary, cross-stitched fabric with exquisite patterns is expected to be a promising sound absorber for potential room acoustics applications.
... Table 2 shows that the airflow resistivity of the normal plain woven fabric sample is higher than those of 5 BYW fabric samples. According to Pieren (2012), the airflow resistivity of thin woven fabric material is negatively correlated to inter-yarn pore diameter and porosity. BYW fabric samples have a larger inter-yarn pore diameter resulting from the thicker weft yarn, and a larger inter-yarn porosity than the normal fabric sample, as shown in Table 2, Fig. 5(a) and (b). ...
In this work, a new band yarn woven (BYW) fabric has been developed to improve the sound absorption of kapok fibrous materials. BYW fabric materials were prepared by the interweaving of the normal hollow polyester yarn with new band yarn produced by wrapping the super thin nonwoven around a twisted fiber web. This soft, thin, lightweight fabric is promising to get the door of a wide variety of agro-sourced kapok fiber for sound absorption applications. The sound absorption of BYW fabric and the normal woven fabric have been compared, and the effects of fiber type, kapok fiber content, and airflow resistivity on sound absorption of BYW fabric materials have also been investigated. The results show that BYW fabric exhibited better sound absorption than the normal fabric, and it can be further enhanced when the band yarn was prepared from kapok fiber instead of hollow polyester or cotton fiber. The sound absorption can be improved with the increasing content of kapok fiber. Furthermore, a new sound absorption empirical model based on the Delany-Bazley model was developed. Calculated sound absorption coefficients obtained from the new model agreed well with measured results. Kapok fiber, exhibits higher hollowness and smaller fiber diameter than common natural fibers, and it presents promising prospect to reduce environmental noise pollution.
... These structures have many applications in building and automotive industries [7][8][9][10]. The fibrous structures are in the form of woven [11][12][13], knitted [14,15], nonwoven [16][17][18][19][20][21] and their composites [22][23][24][25] are increasingly used for sound absorption due to their light weight and low cost. ...
In this work, the sound absorption properties of warp knitted spacer fabrics enhanced with nanofiber were studied. The angle of connecting yarns at two different spacing was considered as knit structure variable. Also, the effect of layering on the sound absorption performance was studied. Besides that, the effect of polyacrylonitrile nanofiber enhancement on sound absorption coefficient of such structures were considered. The polyacrylonitrile nanofibers were manufactured by a single-nozzle electrospinning device using a rotating cylindrical collector. The main variable for the nanofiber enhancement was its deposition amount on the front surface of spacer fabrics. The sound absorption coefficient was measured by using the method of impedance tube. For this purpose, the samples were prepared according to the requirements, and the tests were performed at the frequency range of 500–6000 Hz on single-layer and multi-layer samples. The results showed that increasing the spacing and the angle of connecting yarns will enhance the sound absorption coefficients of samples through increasing their areal mass, thickness and porosity. Moreover, layering will significantly affect the sound absorption performance of samples. Furthermore, nanofiber enhancement increased the absorption of sound at all frequencies.
... The acoustic effects of the mask are modeled as a parallel R-L acoustic circuit. The adopted mask model is based on the models for textile materials, where the effects of the flow through the fabric and movement of the fabric due to the acoustic pressures are considered (Moholkar and Warmoeskerken, 2003;Pieren, 2012). The total flow rate and pressure across the mask are given by ...
In an effort to mitigate the 2019 novel coronavirus disease pandemic, mask wearing and social distancing have become standard practices. While effective in fighting the spread of the virus, these protective measures have been shown to deteriorate speech perception and sound intensity, which necessitates speaking louder to compensate. The goal of this paper is to investigate via numerical simulations how compensating for mask wearing and social distancing affects measures associated with vocal health. A three-mass body-cover model of the vocal folds (VFs) coupled with the sub- and supraglottal acoustic tracts is modified to incorporate mask and distance dependent acoustic pressure models. The results indicate that sustaining target levels of intelligibility and/or sound intensity while using these protective measures may necessitate increased subglottal pressure, leading to higher VF collision and, thus, potentially inducing a state of vocal hyperfunction, a progenitor to voice pathologies.
