• Title, Summary, Keyword: 흡음률

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An Experimental Study on Sound Absorption characteristics of Porous Materials (다공성 흡음재의 흡음률에 영향을 주는 요소에 관한 고찰)

  • 김현태
    • Proceedings of the Acoustical Society of Korea Conference
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    • pp.53-56
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    • 1998
  • 다공성흡음재의 흡음률에 미치는 요소를 실험을 통하여 알아보았다. 흡음재의 두께, 밀도, 공기층, 표면처리, 흡음재의 조합 등에 따른 흡음률의 변화를 측정하였다. 공기층을 두고 시공하면 저역.중역에서의 흡음률이 현저히 증가하며, 유공판, 판상흡음재 등과 적절히 조합하면 보다 넓은 범위에서 좋은 흡음률을 갖게 됨을 알 수 있다. 또한 최대흡음률을 갖는 두께가 λ/4로 예상되지만, 흡음재의 구조에 따라 음의 경로의 유효길이가 늘어나 그보다 작은 두께일 것으로 예상된다.

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Improvement of Sound Absorption Capability of Wood and wood-based Board by Resonant Absorption (공명흡음에 의한 목재와 목질보드의 흡음성능개선)

  • Kang, Chun-Won;Park, Hee-Jun
    • Journal of the Korean Wood Science and Technology
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    • v.29 no.1
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    • pp.16-21
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    • 2001
  • Improvement of sound absorption capability of wood and wood-based board by resonant absorption was attempted. Sound absorption coefficients of wood and wood-based board which contain normal, simple perforation and stair type perforation had been estimated by the tube method using standing wave ratio. Sound absorption coefficients of wood specimens of simply perforated and perforated with stair were higher than that of normal specimens. Especially, in case of stair type perforation, it was about 50 to 60% higher than that of normal specimen in the frequency of 3 to 4KHz. It was considered that the cavity which had been formed by perforation with stair type behaved as a single resonator. Wood-based board showed good sound absorption coefficients in the frequency from 125Hz to 2KHz and that of perforated board showed a little higher in the frequency from 300Hz to 500Hz than that of normal board. The computed data of resonant frequencies at several sizes of cavity showed good accordance with the estimated data of those.

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Effects of sound absorbent gypsum board in the ceiling on low-frequency heavyweight floor impact sound (흡음 석고보드 천장재에 의한 저주파 중량 바닥충격음의 저감 효과)

  • Song, Han-Sol;Ryu, Jong-Kwan
    • The Journal of the Acoustical Society of Korea
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    • v.37 no.5
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    • pp.323-330
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    • 2018
  • This study investigated effects of absorbent gypsum board in the ceiling on low-frequency heavyweight floor impact sound through sound absorption coefficient and floor impact sound measurement. The sound absorption coefficients were measured with sound absorbent gypsum board, glass wool on gypsum board, and a double panel absorbent gypsum board (absorbent gypsum board + glass wool + absorbent gypsum board). Result showed that the absorbent gypsum board had sound absorption coefficient of 0.1 ~ 0.7 from 200 and 630 Hz octave band. The sound absorption coefficient was increased in all frequency range by adding glass wool. Additional absorbent gypsum board increased sound absorption coefficient up to 250 Hz octave band, but decreased over 250 Hz. Heavyweight floor impact sounds were measured in test building for three materials above, gypsum board, and bare slab. Result showed that glass wool on gypsum board and a double panel absorbent gypsum board reduced by 3 dB ~ 4 dB (single number quantity) heavyweight floor impact sound. Comparing with bare slab condition, floor impact sound reduction was mainly found from 125 Hz to 500 Hz octave band, and the maximum reduction was shown in the 250 Hz octave band.

Experimental Investigation of Factors Influencing Chair Absorption Characteristics (의자 흡음특성에 영향을 미치는 인자에 관한 실험적 연구)

  • Choi, Young-Ji;Koo, JaeOh
    • The Journal of the Acoustical Society of Korea
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    • v.34 no.4
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    • pp.282-287
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    • 2015
  • This paper examines the combinations of factors influencing the absorption characteristics of theatre chairs. One-tenth scale model chairs and listeners that closely approximated the absorption characteristics of full scale theatre chairs were used to measure the interactive effects of the test variables on the chairs absorption characteristics. The test variables were the type of chairs, the row spacing, as well as the presence of people and carpet. The variations of absorption increments with varied row spacing tended to be smallest when the chairs were less absorptive, i.e. with less carpet or occupants. The incremental effects of adding occupants or carpet averaged over three row spacings varied over frequency.

Analysis of Sound field in a Reverberation room (잔향실의 음장해석)

  • 권영필;임정빈;이주원;이득웅
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.124-129
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    • 1996
  • 잔향실의 내부 음장을 해석한 결과 다음과 같은 결론을 얻을 수 있었다. 1) 벽면의 흡음률이 동일한 경우는 음향 임피던스의 실수항과 허수항의 변화, 즉 위상의 변화에 따른 음장의 변화가 없다. 2) 5각 형태의 잔향실은 벽면의 흡음률 변화에 따른 음장의 변화가 없다. 3) 4각 형태의 잔향실은 5각 형태의 잔향실보다는 음장이 불균일하며 벽면의 흡음률이 증가함에 따라 음압레벨이 표준편차가 커진다.

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Consideration on correlation between normal and random incidence abrorption coefficient (수직 및 랜덤입사 흡음률의 상관관계 고찰)

  • Kang, Hyun-Ju;Kwak, Yeun-Keun;Cheon, Oh-Sung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.886-889
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    • 2002
  • In order to evaluate absorption coefficient, experimental works for normal and random incident absorption coefficient are made. An investigation for correlation between normal and random incident absorption was carried out by experiment and analysis. It appears that at the low frequencies, the random incident absorption is higher than the normal one, whileas at the high frequencies, the random incident absorption is decreased due to the effect of grazing incident components.

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Sound Absorption Material Using Aluminum Sash (알루미늄 새시를 이용한 흡음구조)

  • Kim, Jung-Joong;Jeong, Jeong-Ho;Sohn, Jang-Yeul
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.201-204
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    • 2007
  • 다양한 공연장 및 대공간에서의 실내음향 제어를 위해서는 실내마감재료의 흡음 및 확산성능을 제어할 수 있는 재료가 필요하다. 본 연구에서는 이를 위해 알루미늄 새시를 이용한 흡음구조를 개발하였으며, 흡음특성을 조사하기 위하여 수직입사 흡음계수와 잔향실법 흡음계수를 측정하였다. 수직입사 흡음계수 측정결과 알루미늄 다목적 흡음재의 타공구조와 인서트에 의해 형성되는 공간이 공명형 흡음기의 역할을 하여 중.저주파수 대역의 흡음계수가 증가되는 것으로 나타났다. 잔향실법 흡음계수 측정결과 알루미늄 새시를 이용한 흡음구조의 형성에 따라 공명주파수 대역보다 낮은 중저주파수 대역의 흡음계수가 증가되는 것으로 나타났다. 공기층 증가에 따라 공명주파수 이상 대역에서의 흡음률은 증가되고 주파수 대역별 흡음계수 편차도 감소되는 것으로 나타났으며, 고주파수 대역의 흡음률 향상을 위한 방안이 필요한 것으로 나타났다.

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A Study on the Sound Absorption Properties of Cellular Concrete with Continuous voids (연속공극을 갖는 기포콘크리트의 흡음특성에 관한 연구)

  • Lee, Seung-Han;Jung, Yong-Wook;Park, Jung-Jun
    • Journal of the Korea Concrete Institute
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    • v.15 no.4
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    • pp.566-573
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    • 2003
  • This study was performed to manufacture a rigid sound absorbing material by increasing the continuous void ratio of cellular concrete, thereby achieving an increase in sound absorption ratio and an enhancement in strength of the cellular concrete. By the experiments, it was determined that an increase in sound absorption ratio is achieved by increasing the added amount of air voids, thereby increasing the continuous void ratio. When the material had a thickness of 5 cm, a satisfactory average sound absorption ratio of 70% was obtained at a continuous void ratio of 40% or more. An increase in the thickness of the sound absorbing material resulted in an increase in sound absorption ratio in a super bass range. The specific gravity of cellular concrete meeting an average sound absorption ratio of 70% was 0.4 at a material thickness of 5 cm, and 0.6 or less at a material thickness of 7 cm. The compressive strength of the cellular concrete having a specific gravity of 0.4 meeting an average sound absorption ratio of 70% or more was 1.37 Mpa at a cement fineness of 3,000. This compressive strength was increased to 3.34 MPa at a cement fineness of 8,000. Accordingly, it was determined that the compressive strength of cellular concrete having continuous voids increases with a higher cement fineness.

Effect of surface density on sound absorption of acoustical reflectors (음향반사판의 밀도별 특성)

  • Jeong, Jeong-Ho;Jeon, Jin-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.272-275
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    • 2008
  • 공연장음향성능에 영향을 미치는 중요한 부자재중의 하나인 음향반사판의 면밀도 변화에 따른 흡음특성 변화를 조사하였다. 음향반사판은 목질계반사판으로 밀도 변화는 $11\;㎏/m^2{\sim}41k\;㎏/m^2$으로 총 3개의 시료를 대상으로 측정하였다. 저주파 대역에서의 흡음률을 측정하기 위하여 서브우퍼와 무지향성 스피커를 사용하였으며 측정결과 중고주파수 대역의 흡음률은 면밀도 변화에 따라 큰 차이가 없었으나 저주파수 대역의 흡음률을 면밀도 변화에 따라 차이가 있는 것으로 나타났다. 향후 음악 공연 공간내의 음향반사판의 면밀도 변화에 따른 실내 음향 특성 변화 및 설계지침에 대한 연구가 필요할 것으로 사료된다.

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Effect of Structure on the Sound Absorption and Sound Transmission Loss of Composite Sheet (복합시트의 구조가 흡·차음성에 미치는 영향)

  • Lee, Byung-Chan;Kim, Sung-Ryong
    • Composites Research
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    • v.25 no.5
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    • pp.154-158
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    • 2012
  • The effect of structure on the sound absorption and sound transmission loss of composite sheet was investigated. A sheet of polypropylene was bonded by hot press with nonwoven fabric sheets of polyethylene terephthalate on the top side and the back side. Absorption coefficient of composite sheet using nonwoven fabric with surface density of $0.64kg/m^2$ was 0.1-0.2. It is 100-400% improvement compare to that of polypropylene sheet. The transmission loss of composite sheet was increased with surface density of polypropylene board and introduction of hemisphere hole on the surface of sheet. Two types of composite sheet were made using flat sheet and sine wave shaped sheet and the effect of sheet structure on the transmission loss was investigated.