• Title/Summary/Keyword: Reverberation room

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A Study on the Room Acoustics in Churches (교회 건축물의 실내음향 특성에 관한 연구)

  • 주진수
    • Journal of KSNVE
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    • v.9 no.4
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    • pp.681-686
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    • 1999
  • In a church, speech intelligibility is very important together with the reverberance for musical activities. In order to obtain the primary data of a acoustical design for churches records were refereed and churches were measured in Europe and Japan. And in the base of measurements, those were judged by subjective hearing test. As some results, it has been found that the room acoustics of churches were different in a country and the reverberation time was perferred two seconds for speech intelligibility. However, although personal deviations were admitted, more long echoes were preferred for the music.

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Constraints for the Design of Room Reverberation Filter by Using 5-DOF Reverberation Model (5자유도 잔향 모델을 이용한 실내 잔향 필터 설계를 위한 조건)

  • 김소희;김양한
    • The Journal of the Acoustical Society of Korea
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    • v.20 no.2
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    • pp.58-65
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    • 2001
  • Recently, a 5-degrees-of-freedom (DOF) reverberation model was proposed as a method of representing subjective perception of reverberation as objective measures[1]. This model approximates sound energy decay curve by five objective measures, widely used in which have been concert hall acoustics. However, it is note worthy that there can be infinite number of impulse responses which correspond to a selected 5-DOF reverberation model. There may exist some filters making very unnatural and unrealistic sound. In this paper, the limitation of the 5-DOF reverberation model when it is used as a filter design criteria is investigated. When a 5-DOF reverberation model is given, additional constraints to get natural reverberation are suggested. This is based on the listening tests for several quite different source sounds.

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The Study on Correction Factor of a Small Scale Reverberation Chamber to Estimate Transmission Loss (소형 잔향실의 확산 음장 보정 계수 측정 연구)

  • Kim, Tae Min;Kim, Da Rae;Kim, Jeung Tae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.960-965
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    • 2014
  • Transmission loss of specimen is calculated by measuring energy of incident and transmission and using reverberant room of large size. But normal measurement of transmission loss has trouble because it is actually demanded that large area and specimen of certain size is satisfied with condition of diffused sound field. Especially, in case of mechanical component, interested frequency band is mid-frequency band between 500 ~ 2k Hz, and it is used to be available to minimize a reverberation chamber under conditions satisfying acoustic one because production of specimen for transmission loss measurement has limit. But, as in semi-reverberation room, it is difficult to satisfy condition of diffuse sound field and modification factor is applied to complement that. Correction factor when measuring transmission loss using semi-reverberation chamber is required accuracy because it works as main factor determining reliability of reuslts on transmission loss. In this study, it is analyzed that an effect on correction factor based on varying materials and sizes of specimens in order to deduction of it. Also It is confirmed that applied by elicited correction factor with actual railway vehicle's floor has reliability.

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Study on method of build up low-frequency diffuse sound field in a scaled reverberation chamber (축소잔향실의 저주파수 확산음장 형성 방법에 대한 연구)

  • Kang, Jun-Goo;Kang, Hyun-Ju;Kim, Sang-Ryul;Choi, Jong-Soo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.61-64
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    • 2007
  • This study is dealt with a method to enhance low-frequency diffuse sound field in a scaled reverberation chamber. Because scaled reverberation chamber has not enough room volume, as a result, it shows a few room modes. So it is not build up low-frequency diffuse sound field. A Helmholtz resonator's arrangement is used to improve spatial uniformity of sound pressure at low frequency. The spatial distribution of sound field has been measured before and after control. The standard deviation of sound field has decreased at 315Hz 1/3 Octave band.

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Korea Industrial Standardization Draft for ISO 354 (ISO 354 (잔향실법 흡음률 측정방법)의 KS 규격화)

  • Jung, Sung-Soo;Kook, Chan;Kim, Sun-Woo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.857-860
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    • 2003
  • We introduced the basic direction of revision for KS F 2805 (method for measurement of sound absorption coefficient in a reverberation room). It is fundamentally equal to ISO 354 (measurement of sound absorption in a reverberation room) which was state of ISO/FDIS 354. Two main points were strongly reviewed. First, the sound absorption coefficient values for Type J test specimen mounting was investigated. Next, the reverberation time difference between the conventional method and new additional one, impulse response method were compared.

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A Study on the Improvement of Reverberation Room's Performance (잔향실 성능 검증 및 향상 연구)

  • Kim, Sung-Hoon;Joo, Won-Ho;Kim, Dong-Hae;Bae, Jong-Guk
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.171-175
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    • 2006
  • Recently, two reverberation rooms were built up of 300mm thick concrete walls in non-parallel pentagonal shape to measure the sound absorption, transmission, radiation, and impact insulation of acoustical materials, panels, doors, etc. Various acoustic tests, including the sound transmission test, were carried out to investigate their acoustic performances. In order to improve the performance, several modifications on these acoustical parameters, such as the acoustic mode, the position of specimen, the formation of diffuse field, the location of sound source, and flanking transmission, have been conducted. Through a series of tests, the reverberation rooms have been effectively improved so that it could perform a variety of acoustic tests with the international standard. And then, it is expected to be very helpful in developing the low noise design technology for ships.

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Effect of the measurement error of reverberation time on the STL (잔향시간 측정 오차의 차음손실에 대한 영향)

  • 신성환;이정권;강현주
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11b
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    • pp.1099-1103
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    • 2001
  • In room acoustics, reverberation time (RT) is the most important and general factor that represents character of room or inner space. However, RT, especially in low frequency range, can have the different value according to the measuring points and methods. This study comprehends the cause of error occurring dominantly in low frequency range when RT is measured and examines that the each error of RT measured in the cabin and reverberation chamber having different properties, influences what extent on sound transmission loss (STL)

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An Experimental Investigation on Noise Reduction Performance of the Absorption and the Resonance Type Duct Silencers (흡음형과 공명형 덕트 소음기의 소음저감 성능에 관한 실험적 고찰)

  • Lee, Young-Sup;Chung, Kwang-Seop;Lee, Dong-Hoon
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.22 no.12
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    • pp.897-901
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    • 2010
  • A silencer has been widely used for the purpose of suppressing the noises propagated from duct of air conditioning system. The absorption type silencer is usually applied to reduce the noise with high frequency bandwidth. On the order hand, the resonance type silencer is applied to reduce the noise with low-middle frequency bandwidth. The insertion loss of silencer is measured in the reverberation room. The cut-off frequency of reverberation room is 100 Hz. The insertion loss of absorption type silencer is more larger than that for resonance type silencer regardless of changing the flow velocity.

A measuring technology of the absorption ratio and the transmission loss using the tube method (관내법을 이용한 흡.차음 성능 측정방법)

  • 이장명;김동률
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1998.04a
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    • pp.659-663
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    • 1998
  • To measure the absorption ratio and the transmission loss of a material, a usage of the reverberation room has been popular. However, the reverberation room is expensive to build it and, sometimes, test procedure is not easy. Therefore, to get the data of absorption ratio, several possible technologies has been proposed using the tube. Among these technologies, with the analysis of the spectral density, a convenient method has been introduced to measure both the absorption ratio and transmission loss. The measured data has been compared with the results of the measurement at the reverberation room.

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An Analysis of Sound Pressure Distribution in a Reverberation Room and Comparisons with Measurements (잔향실의 음압분포해석 및 계측치와의 비교)

  • 김현실;김재승;강현주;김상렬
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1997.04a
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    • pp.669-674
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    • 1997
  • A sound field in a reverberation room is analyzed by using numerical methods and the SPL distributions are compared to the measurements. In numerical predictions, the BEM is employed in the low frequency range, while sound ray tracing method is used for the high frequency range. In the BEM analysis, the surfaces of the empty reverberation room are assumed as rigid boundaries and the damping coefficients are estimated from the measured absorption coefficient. The comparisons with measurements for 100Hz shows good agreement. In the sound ray tracing analysis, the predicted energy decay are in excellent agreements with theoretical results. It is shown that the energy absorption by air damping plays an important role as frequency becomes higher.

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