Sound Absorption Coefficients of Micro-fiber Fabrics by Reverberation Room Method

Na, YoungJoo,Lancaster, Jeff,Casali, John,Cho, Gilsoo Sage Publications 2007 Textile research journal Vol.77 No.5

<P>The sound absorption properties of materials are important not only for noise reduction, but also for controlling reverberation time for speech intelligibility in rooms and for promoting fuller sound in concert halls. Industrial textiles are focusing on these materials' application for sound absorption, thus new textiles were to be examined in relation to this performance. Micro-fiber fabric has fine fibers and a high surface area and it has been used in such applications as wipers, thermal insulator, filters or breathable layers. It can be also used for sound absorption. This paper examines the possibility of using micro-fiber fabrics as sound absorbent materials. We tested the sound absorption coefficients of five micro-fiber fabrics and one regular fiber fabric by the reverberation room method. The results showed that the micro-fiber fabrics' sound absorption is superior to that of conventional fabric with the same thickness or weight, and the micro-fiber fabrics' structure was found to be important for controlling sound absorption according to sound frequency. Fabric density was found to have more effect than fabric thickness or weight on sound absorption, and the Noise Reduction Coefficient increases to its highest value at a fabric density of about 0.14 g/cm3, and it decreases thereafter.</P>

소리특성과 생리적 반응을 이용한 편성물의 소리디자인 시스템(I) -위편성물의 소리특성과 역학적 특성-

조길수,김춘정,Cho, Gil-Soo,Kim, Chung-Jeong 한국섬유공학회 2006 한국섬유공학회지 Vol.43 No.5

This research aimed to analyze the mechanical properties and sound characteristics of weft knitted fabrics for establishing database of sound design system for knitted fabrics. The specimens consisted of 27 weft knitted fabrics. Mechanical properties of the knitted fabrics were measured with Kawabata evaluation system (KES). The frictional sounds of specimens were recorded by a sound generator and transformed into sound spectrum by FFT. The level pressure of total sound (LPT), level range ($\Delta$f), and frequency difference ($\Delta$f) were calculated from the sound spectra obtained in the FFT analysis. Zwicker's psychoacoustic parameters such as loudness(Z), sharpness(Z), roughness(Z), and fluctuation strength(Z) were calculated. The weft knitted fabrics have similar values of roughness(Z) and fluctuation strength(Z). Polyester fabrics with low elongation at maximum load (EM) and high coefficient of friction(MIU) showed the loudest and the sharpest frictional sound. The lyocell fabrics with low bending properties (B, 2HB) and thickness showed the most quiet and softest frictional sounds. Bending properties, surface properties, thickness and weight in weft knitted fabrics showed high relationship with the physical and psychoacoustic properties of frictional sound.

블라우스용 직물의 소리 특성과 태

조길수,이은주 한국의류학회 2000 한국의류학회지 Vol.24 No.4

This study was carried out to investigate sound characteristics including sound parameters and subjective sensation, and primary hand values related with sound of fabrics for blouse, and furthermore to predict subjective sound sensation with mechanical properties and sound parameters. Sound of specimens was analyzed by FFT. Level pressure of total sound(LPT), loudness(Z), coefficients of autoregressive(AR) functions for fitting the spectra, and sound color factors(ΔL and Δf) were obtained as sound parameters. Primary hand values for women's thin dress were calculated by using KES-FB. Subjective sensation for sound including softness, loudness, sharpness, clearness, roughness, highness, and pleasantness was evaluated by free modulus magnitude estimation. The results were as follows, 1. Fabrics for blouse showed similar spectral shapes to one another in that amplitude values were lower in most ranges of frequencies than fabrics for other uses. 2. It was found that fabrics for blouse were less louder because LPT, loudness(Z), and ARC values were lower than other fabrics. 3. Primary hand values indicated that specimens were soft-touched, flexible, and less crisp. Among primary hands related with sound, Shari values were higher for silk fabrics than for synthetic ones, while the values for Kishimi were similar. 4. Fabrics for blouse were rated more highly for softness, clearness, and pleasantness than for loudness, sharpness, roughness, and highness. Silk fabrics were evaluated more pleasant than synthetic fabrics. 5. Subjective sensation for sound of blouse fabrics were predicted with mechanical properties and physical sound parameters.

신체 동작을 모사한 직물마찰음 발생장치의 개발 및 이를 이용한 직물 마찰음 평가

이규린,이유진,박해리,조길수,Lee, Kyulin,Lee, Eugene,Park, Haeli,Cho, Gilsoo 한국섬유공학회 2013 한국섬유공학회지 Vol.50 No.4

To investigate the sound generated by fabric friction, which simulates real wear conditions, a 'fabric friction sound generator', which simulates body movement was developed. Fabric sounds from three specimens were generated by the fabric sound simulator and recorded using high performance microphones. Physical sound parameters such as sound pressure level (SPL), level range (${\Delta}L$), and frequency difference (${\Delta}f$) were calculated for the fabrics. All the physical parameters (SPL, ${\Delta}L$, and ${\Delta}f$) of fabric sounds generated by the fourth-generation apparatus had lower values compared to the values obtained with the third-generation apparatus. Unlike the third-generation system, which generates fabric sounds by reciprocating friction, the fourth-generation system was designed with silicon-based arm-and-leg shaped abraders so that the levels of noise and fabric sounds generated were lower at all speeds.

태권도 도복 직물의 소리 특성과 역학적 성질

진은정 ( Eun Jung Jin ),조길수 ( Gil Soo Cho ) 한국의류산업학회 2012 한국의류산업학회지 Vol.14 No.3

This study examined the sound characteristics of Taekwondo uniform fabrics to investigate the relationship between the sound parameters and the mechanical properties of the fabric as well as to provide the conditions to maximize the frictional sound of the uniform. Frictional sounds of 6 fabrics for Taekwondo uniforms were generated by the Simulator for Frictional Sound of Fabrics. The frictional speeds were controlled at low (0.62 m/s), at mid (1.21 m/s) and at high (2.25 m/s) speed, respectively, The frictional sounds were recorded using a Data Recorder and Sound Quality System subsequently, the physical sound properties such as SPL (Sound Pressure Level) and Zwicker`s psychoacoustic parameters were calculated. Mechanical properties of specimens were measured by KES-FB. The SPL, Loudness (Z) values increased while Sharpness (Z) value decreased. In the physical sound parameter, specimen E had the highest SPL value at low speed and specimen B at high speed. In case of Zwicker`s psychoacoustic parameters, the commercially available Taekwondo uniform fabrics (E, F) showed higher values of Loudness (Z), Sharpness (Z), and Roughness (Z), that indicates they can produce louder, shaper and rougher sounds than other fabrics for Taekwondo uniforms. The decisive factors that affected frictional sounds for Taekwondo uniforms were W (weight) as well as EM (elongation at maximum load) at low speed and WC(compressional energy) at high speed.

Prediction Models for Audible Distance Using Mechanical and Psychoacoustic Parameters of Combat Uniform Fabrics

Lee, Jeehyun,Cho, Gilsoo THE KOREAN FIBER SOCIETY 2014 FIBERS AND POLYMERS Vol.15 No.3

A short audible distance for the rustling sound of combat uniform fabric helps to reduce soldiers' exposure to the enemy forces. The objectives of this study were to evaluate mechanical properties and sound characteristics of combat uniform fabrics, to investigate their influence on audible distance at which fabric's rustling sound can be reached to human ear, and to establish prediction models for audible distance using mechanical and psychoacoustic parameters. Six types of combat uniform fabrics were used as test specimen. Mechanical properties of the specimens were measured according to the KES-FB system and the acoustic characteristics of the fabrics were analyzed by the Sound Quality System. Audible distances of the fabric sounds were assessed by 30 male soldiers. The audible distances were determined by the distance of which the participants walked away from a starting point in a straight line until they could not hear the sound. Water repellent finished fabric (W-WR), which showed the highest values of bending rigidity, shear stiffness, sound pressure level, loudness(Z) and sharpness(Z) among all fabrics, had the longist audible distance. Fabric for summer season (W-S) had the shortest audible distance in all frictional speed levels, which indicates the best auditory camouflage performance. Coefficient of friction was chosen as the variable affecting loudness(Z) of fabric sounds. Loudness(Z) was finally chosen as the prediction parameter for the audible distance by path analysis.

Fabric Sound Depends on Fiber and Stitch Types in Weft Knitted Fabrics

Cho, Soomin,Cho, Gilsoo,Kim, Chunjeong SAGE Publications 2009 Textile Research Journal Vol.79 No.8

<P>The purpose of this study is to analyze the characteristic fast Fourier transform (FFT) spectra of weft-knitted fabrics, to investigate the relationship between sound parameters and the mechanical properties of the weft knits, and to determine the effects of fiber type and stitch type on the frictional sound and mechanical properties. The specimens included 12 weft-knitted fabrics made from a combination of 3 fiber types (100% wool, 100% cotton and 49%/51% wool/ cotton) and 4 stitch types (plain, rib, half cardigan and half milano stitch). The rustling sounds of each specimen were recorded and analyzed using FFT analysis including sound parameters such as LPT (level pressure of total sound), Δ<I>L</I> (level difference) and Δ<I>f</I> (frequency difference). We also used Zwicker's psychoacoustic model to calculate the loudness (<I>Z</I>), sharpness (<I>Z</I>), roughness (<I>Z</I>) and fluctuation strength (<I>Z</I>). In addition, the mechanical properties of the specimens were measured using the Kawabata Evaluation System (KES). The FFT spectra for the weft-knitted fabrics showed different shapes according to the fiber and stitch types. Mechanical properties such as the thickness and weight were correlated with several sound parameters. Fiber type was affected by Δ<I> f</I> and stitch type was affected by Δ<I>L</I>, roughness (<I>Z</I>), fluctuation strength (<I>Z</I>) and weight. Both fiber type and stitch type were affected by tensile properties. It is possible, by changing fiber and stitch types of weft-knitted fabrics, to obtain various kinds of knitted fabrics with different frictional sounds.</P>

Effect of Fabric Sound and Touch on Human Subjective Sensation

Cho, Gilsoo,Casali, John G.,Yi, Eunjou The Korean Fiber Society 2001 Fibers and polymers Vol.2 No.4

In order to investigate the relationship between subjective sensation for fabric sound and touch and the objective measurements, eight different apparel fabrics were selected as specimens. Sound parameters of fabrics including level pressure of total sound (LPT), level range (ΔL), and frequency differences (Δf) and mechanical properties by Kawabata Evaluation System (KES) were obtained. For subjective evaluation, seven aspects of the sound (softness, loudness, pleasantness, sharpness, clearness, roughness, and highness) and eight of the tough (hardness, smoothness, fineness, coolness, pliability, crispness, heaviness, and thickness) were rated using semantic differential scale. Polyester ultrasuede was evaluated to sound softer and more pleasant while polyester taffeta to sound louder and rougher than any other fabrics. Wool fabric such as worsted and woolen showed similar sensation for sound but differed in some touch sensation in that woolen was coarseast, heaviest, and thickest in touch. In the prediction model for sound sensation, LPT affected positively subjective roughness and highness as well as loudness, while ΔL was found as a parameter related positively with softness and pleasantness. Touch sensation was explained by some of mechanical properties such as surface, compressional, shear, and bending properties implying that a touch sensation could be expressed by a variety of properties.

Membrane구조를 갖는 섬유 집합체형 흡음재의 흡음 인자 결정에 관한 연구

장효준,전두환 한국섬유공학회 2004 한국섬유공학회지 Vol.41 No.4

Basic mechanism of sound absorption in various sound absorbing materials is generally explained by the conversion of sound energy into heat energy. The important element governing the conversion from sound into heat depends on the material characteristics. Three types, such as porous, resonance and panel types, generally classify the geometrical structure of sound absorbers. These three types of sound absorbing materials demonstrate different sound absorption characteristics. In this study, for the absorption of the specific sound frequency, various parameters are investigated experimentally using the impedance tube method. The models used in the experiment are porous and panel type absorbers. The porous type absorber generally has the ability of sound absorption at the high frequency range and the panel type absorber has the capability of sound absorption of the specific sound frequency. The sound absorption characteristics of the panel type absorber are described in phenomenon related to the sound absorption characteristics of porous type products. Detail experiments are carried out to clarify the parameters governing the acoustic performance with different fabrics.

스포츠웨어용 투습발수직물 소리가 심리음향학적 특성에 미치는 영향

이지현 ( Jee Hyun Lee ),이규린 ( Kyu Lin Lee ),진은정 ( Eun Jung Jin ),양윤정 ( Yoon Jung Yang ),조길수 ( Gil Soo Cho ) 한국감성과학회 2012 감성과학 Vol.15 No.2

본 연구에서는 심한 소음으로 불쾌감을 주는 스포츠웨어용 PTFE 라미네이팅 투습발수 직물 8종을 대상으로 직물 마찰음의 심리음향학적 특성을 고찰하고, 심리음향학적 특성에 영향을 미치는 직물의 기본 특성과 역학적 특성 간의 관계를 파악함으로써, 직물의 심리음향학적 마찰음을 낮출 수 있는 변인을 찾아내고자 하였다. 직물 마찰음 시뮬레이터를 이용하여 녹음한 직물의 소리에서 Zwicker의 파라미터인 심리음향학적 크기(loudness(Z)), 날카로움(sharpness(Z)), 거칠기(roughness(Z)), 그리고 변동강도(fluctuation strength(Z))를 계산한 뒤, 소리특성에 대한 사후검정 결과에 따라 시료를 덜 시끄러운 PTFE 필름 그룹과 더 시끄러운 PTFE 필름 그룹으로 나누어 마찰음의 심리음향학적 특성과 직물의 역학적 특성, 기본특성간의 관계를 고찰하였다. 심리음향학적 특성 중 loudness(Z)만이 시료의 마찰음과 유의한 관계에 있는 것으로 나타났으며, 분석 결과 직물의 기본 특성에서는 layer가 얇고 필라멘트사를 사용한 직물의 마찰음이 덜 시끄럽게 인지되는 것으로 나타났으며, 직물 마찰음의 심리음향학적 크기에 영향을 미치는 주요변수로는 layer로 것으로 나타났다. 심리음향학적 크기에 영향을 미치는 주요 역학변수로는 전단이력이 설명 변인으로 포함되었다. The objectives of this study were to investigate the psychoacoustic properties of PTFE(Poly tetra Fluoroethylene) laminated vapor permeable water repellent fabrics which are frequently used for sportswear, to examine the relationship among fabrics`` basic characteristics, mechanical properties and the psychoacoustic properties, and finally to propose the predicting model to minimize the psychoacoustic fabric sound. A total of 8 specimens`` frictional sound were recorded and Zwicker`s psychoacoustic parameters such as loudness(Z), sharpness(Z), roughness(Z), and fluctuation strength(Z) were calculated using the Sound Quality Program. Mechanical properties of specimens were measured by KES-FB system. Loudness (Z) of specimen D-1 was the highest, which means the rustling sound of the specimen D-1 was the most noisy, Statistically significant difference among film type was observed only in loudness (Z) for fabric sound, Based on ANOVA and post-hoc test, specimens were classified into less loud PTFE film group (groupⅠ) and loud PTFE film group (groupⅡ). Loudness (Z) was higher when staple yarn was used compared when filament yarn was used. According to the correlation between the mechanical properties of fabrics and loudness(Z) in groupⅠ, the shear properties, compression properties and weight showed positive correlation with loudness(Z). According to the regression equation predicting loudness(Z) of groupⅠ, the layer variable was chosen. In groupⅡ, variables explaining the loudness(Z) were yarn types and shear hysteresis(2HG5).