• Title, Summary, Keyword: Sound characteristics

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Experimental Study to Determine Sound Absorption Factors of Fiber Assemblies with Membrane Structure (Membrane구조를 갖는 섬유 집합체형 흡음재의 흡음 인자 결정에 관한 연구)

  • 장효준;전두환
    • Textile Science and Engineering
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    • v.41 no.4
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    • pp.285-290
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    • 2004
  • 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.

A Study on the Characteristics of Sound Insulation at the Circular Voided Concrete Floor in the Multi-Housing (공동주택에서 중공 슬래브 바닥의 차음 특성에 관한 연구)

  • 손철수
    • Journal of the Korean housing association
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    • v.11 no.1
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    • pp.171-181
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    • 2000
  • The purpose of the resent research is to investigate the characteristics of sound insulation at the circular voided concrete slab in the multi-housing. In order to do this research, the method for field measurement of floor impact sound level was used following the Korea Standard F2810-1996. For the multi-housing, three kinds of circular voided concrete slabs are used to measure the characteristics of sound insulation.The results are as follows; 1.The main factor affecting the characteristics of sound insulation at the circular voided concrete slab in the multi-housing is sound-absorbing materials in the circular tube. 2. The main factor to effect the difference of sound pressure level is circular tube in the concrete slab. 3. The forms of circular tubes effect the characteristics of sound insulation at the circular tube. 4. Sound Pressure Level resulting from the piping direction of circular tubes in little different to octave band level.More study will be needed about the depth and distance of sound insulation materials, and the components of sound insulation materials for the multi-housing.

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Sound Absorption Characteristics of Permeable Membrane (통기성을 갖는 막재료의 흡음특성)

  • Jeong, Jeong-Ho;Kim, Jung-Joong;Kim, Ku-Je
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.270-275
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    • 2009
  • Sound absorption characteristics of membrane system which are used in stadiums and arenas were investigated. Theoretical studies on acoustic properties of single and double leaf permeable membrane conducted. Also, experimental studies on sound absorption characteristics of combined membrane system that is composed of outer and inner membrane material were conducted. In this study, sound absorption characteristics of each membrane were investigated by experiments in reverberation chamber. 4 types of permeable membranes and a non-permeable membrane were used for experiments. Air space behind membrane material and tension on the membrane was varied. Sound absorption performance of permeable membrane materials was confirmed. As increasing air space behind the membrane material, sound absorption coefficient was increased. In a resonance absorption frequency band sound absorption coefficient varied more dramatically. Sound absorption characteristics were flat in mid and high frequency range and sound absorption coefficient was from 0,3 to 0,5. Also sound absorption coefficient was increased by the increment of surface density and air permeability of membrane. However, over the certain value of air permeability, sound absorption coefficient was decreased. These results can be used as design factors and method for the room acoustic design of dome-stadiums and large free-form buildings.

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Sound quality characteristics of heavy-weight impact sounds generated by impact ball (임팩트 볼에 의한 중량 충격음의 Sound Quality 특성)

  • You, Jin;Lee, Hye-Mi;Jeon, Jin-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.671-674
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    • 2006
  • Heavy-weight impact sounds generated by impact ball were classified according to the frequency characteristics on the equal loudness contours. Sound quality metrics such as Zwicker's loudness, sharpness, roughness of each classified impact sound were also measured. Loudness spectrum has been regarded as an indication of the characteristics difference of each classified impact sound. The adjectives in Korean expressing the sound quality characteristics of floor impact sounds were also investigated by adoptability and similarity tests. The group of the adjectives was used to evaluate the sound quality of floor impact sound by semantic differential test method.

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Sound Absorption Characteristics of Audience Seats (공연장 의자의 흡음성능 평가)

  • Jeong, Jeong-Ho;Seo, Chun-Gi;Jeon, Jin-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.589-590
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    • 2008
  • Sound absorption characteristics of audience seating is very important when design and simulate room acoustics of concert halls or multi-purpose auditoriums. Sound absorption characteristics of audience seats were measured in reverberation chamber by varying the row to row spacing and number of audiences. By the increment of the row to row spacing, sound absorption characteristics in mid frequency band was increased. Also, sound absorption was proportionated to the number of audience.

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An Experimental Study on Sound Radiation Characteristics of Radial Tire for a Passenger Car Due to Excitation (가진에 의한 승용차 타이어의 음향방사특성에 관한 실험적 연구)

  • 김병삼;이태근;홍동표
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.10
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    • pp.2426-2436
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    • 1993
  • Vibration characteristics of a tire play an important role to judge a ride conformability and sound quality for a passenger car. In this study, the experimental investigation for the sound radiation of a radial tire has been examined. Based on the sound intensity techniques, the sound pressure field and the sound radiation are measured. It turns out that air pressure in tire, tread patterns, and aspect ratio of the tire govern the sound radiation characteristics. Then a numerical analysis for the tire element is conducted. During analysis, the tire element is modelled as an elastic ring. The comparison shows that the numerical output correlates to the experimental data.

Sound Absorption Characteristics Based on the Woven Fabric Density and Position Variations (메쉬 직물의 밀도 및 위치변화에 따른 흡음특성)

  • Lee, Kyoung Min;Chun, Du Hwan;Chun, Sang Hoo
    • Textile Science and Engineering
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    • v.52 no.3
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    • pp.193-198
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    • 2015
  • Sound absorbing materials are generally categorized as porous-type absorbers and panel-type absorbers. In addition, their absorbing mechanism is typically described as a conversion of sound energy into heat energy through the dynamic behavior of the material. Thus one of the important parameters influencing the sound absorption characteristics is the density of the material. This study investigated the sound absorption characteristics of a mesh fabric based on the mesh density and fabric layering structure. Four different mesh densities (130, 180, 200, and 230 T) combined with five different layering structures were investigated to help understand the mechanism and effect of the sound absorption characteristics. The results indicate that a panel-type absorber has better sound absorption characteristics within a lower frequency range, whereas a porous-type absorber performs better at a higher frequency. In addition, the increased fabric density of the mesh fabric shows a better performance in terms of sound absorption. An empirical equation between the sound absorption coefficient and the fabric density was also derived for further design applications.

Evaluation of Sound Quality for Urban Environmental Sound (도시 환경음의 음질 평가)

  • Park, Hyeon-Ku;Shin, Yong-Gyu;Kim, Hang;Song, Min-Jeong;Kim, Sun-Woo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.529-534
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    • 2005
  • This study performed an physical analysis on the characteristics of urban environmental sound divided into three parts depending on their features. Object sounds were classified into traffic sound, waster sound and spatial sound. Traffice sound was selected because it is dominant sound in urban environment, and water sound is selected because it generally supplies pleasantness in contrast to traffic sound, Finally spatial sound was considered because it represents sound in various places of city having lots of behaviors and types of sound due to them. Physcal analysis was carried out using sound quality indices based on Zwicker's loudness, $L_{Aeq}$(equivalent noise level), Ln(percentile noise level) and other acoutical attributes applied to previous study. Through the analysis, this study aims to compare the acoustical characteristics of urban environmental sound and to provide fundamental data for the evaluation of urban environmental sound.

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Noise Characteristics of Rapier Loom by Noise Source Analysis (소음원 분석에 의한 직기 구조물의 소음 특성)

  • Na, Hae-Joong;Chun, Du-Hwan
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.254-257
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    • 2005
  • Locations and emission characteristics of noise source of rapier loom are important factors greatly. So, noise characteristics of rapier loom were investigated by the noise source identification as a part of experimental methods in this study. To identify the noise sources of the rapier loom sound intensity was measured under machine operation. In addition, frequency spectra of the sound at operator position was measured along with sound intensity to help identify the noise characteristics of the rapier loom. The results indicate that the sound power level occurs along the rapier loom.

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Experimental study for characteristics of diffuse sound field formed by sound source directivity (음원의 지향성이 확산음장 형성에 미치는 영향에 관한 실험연구)

  • Shin, Il-Seop;Cha, Kwang-Seok;Cho, Chang-Geun;Lee, Dae-Woo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1002-1006
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    • 2000
  • It is diffuse sound field that measuring condition of absorption ratio and sound transmission loss for material consist of building are measured in reverberartion room and on-site. In this study, for upkeeping diffuse sound field in reverberation room, it is measured and etimated that sound field is effected according to sound source lacation and characteristics of emission directivity for sound source.

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