• Title/Summary/Keyword: Reverberation room

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Comparison of Absorption Coefficient according to Test Methods (시험방법에 따른 흡음률 비교)

  • Lee, J.W.;Gu, J.H.;Park, H.K.;Kang, Dae-Joon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.5 s.122
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    • pp.373-378
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    • 2007
  • Today, the use of the sound absorptive material is increasing to improve the room acoustics in the auditorium and music hall, etc. Usually, the sound absorption materials have been used to enhance the performance of a noise barrier and improve the room acoustics in construction site. Generally, the sound absorbtion coefficients are the most important factor reflecting the sound absorbtion performance. There are two methods to measure the sound absorption coefficient. The first one is the reverberation room method, and the second is the impedance tube method. In this study, we measure the sound absorbtion coefficients using these two methods, and then we compared the results of the sound absorbtion coefficients to look into the difference of results between reverberation room method and impedance tube method. Also we compared the results of the sound absorbtion coefficients with respect to the size of sample and the volume of reverberation room. From the experiment, we could see that the sound absorbtion coefficients are measured equally for different sample size. But the sound absorbtion coefficients are measured differently according to test methods and test conditions.

Correlation between reverberation time and standing wave (잔향시간과 정재파의 상호관계)

  • 차일환
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.10 no.5
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    • pp.31-38
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    • 1973
  • The Sabine's formula has been widlely used for calculating reverberation time and applied for actual systems. The result of Sabine's method is only same as the reverberation time of one axial wave according to the wave theory. Reverberation time is mainly dependent on the standing waves. In case of the rectangular room the frequencies of three mode covering 250Hz and several intensities at various positions of the room were measures by a spectrograph. It wart found that axial wavers and tangential waves decayed more slowly than oblique waves. The experimental results showed that the amount of axial and tangential wave in a frequency band varies depending on the position in the room. It is concluded that the results give to control reverberation times in a room.

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The Tuning of Reverberation Time in ISO Type Reverberation Room (ISO Type 차음시험실의 음장튜닝 사례)

  • Kim, Kyung-Ho;Han, Hee-Kab
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.1198-1201
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    • 2006
  • ISO 140-1 recommends installing diffusing elements in the room if there are large variations of the sound pressure level caused by strong standing wave. Also it requires that reverberation time should not be long or short. In accordance to this regulation, we adjusted the reverberation time in the range of $1{\sim}2$ sec by using 4 types of diffusing elements. This paper demonstrates how to balance the reverberation time in the range of $1{\sim}2$ sec by using several types of diffusing elements.

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An Experimental Study on the Acoustic Characteristic of Korean Traditional Houses in Chonnam Province (전남 지방 전통주택의 음향특성에 관한 실험적 연구)

  • Lee, Tai-Gang;Kim, Hyung-Ryul;Kim, Hang;Choi, Eun-Suk;Kim, Sun-Woo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.686-689
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    • 2005
  • This study aims to analyzed the acoustics characteristics of Korean Traditional Houses in Chonnam Province varied with lay out and floor plane to reflect the way of control for environmental condition. These houses are surveyed the reverberation time and level difference between rooms of the main living room and other main floored room, master room and kitchen. As a result, the reverberation time of traditional rooms are below 0.6 second, and the sound insulation performance of Korean traditional door are mostly very low grade with D-15. The level difference between rooms are low grade not to meet minimum class except between main living room and master room away from main living building.

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A Subjective Study on the Reverberation Characteristics of Coupled Spaces (음향적으로 결합된 공간의 주관적 잔향감에 관한 연구)

  • Jeong, Dae-Up;Choi, Young-Ji
    • Journal of Korean Association for Spatial Structures
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    • v.8 no.3
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    • pp.65-73
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    • 2008
  • The present work deals with subjective assessments to propose the objective parameter related to the subjective attribute of reverberation in the coupled room varied the aperture opening size. A 1/10 scale model was built and used for the measurements and subjective assessments. For the subjective tests, binaural impulse responses(BIRs) were measured using a dummy head and the measured BIRs were convolved with anechoic recorded music for the presentation over the headphones. The results showed that the perceived reverberation was the largest in the aperture opening size 12.5%(1.97% of mail) room surface area)and decreased with increasing the aperture opening size over 25% (3.94% of main room surface area) in the main room coupled with the secondary reverberant room. In the main room coupled with the secondary absorptive room, there was no changes in the perceived reverberation up to the aperture opening size 6.25%(0.99% of main room surface area) and it gradually decreased with increasing the aperture opening site over 12.5%. The objective parameter, T30/T15, showed a very low correlation with the perceived reverberation in the coupled room varied the aperture opening size but showed a high correlation with a new objective parameter, T30/Tbp, proposed by the authors. Because the late part decay energy more rapidly increases with increasing the aperture opening site than the early and middle part decay energy, the LDT/EDT or T3/T1 is a better quantifier to measure double slopes in the coupled room than the T30/T15.

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Analysis of the Factors affecting Reverberation Time in Small Room (소규모 공간에서의 잔향시간 영향요인 분석)

  • Kim, Myung-Jun;Lee, Byoung-Ki
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.492-497
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    • 2006
  • This study gives the results of the measurements and analysises of the reverberation times in a small room such as apartment houses. We measured the RT by changing measurement conditions, which were sound sources. sound source's positions, receiving point & height, sampling time and so on. The critical factor affecting reverberation time was sound source in unoccupied houses and the reverberation time differences between result of RT using impulsive and interrupted sound source was 0.3sec at 500Hz frequency. And the difference of RT due to sound sources affected the sound insulation such as apparent sound reduction index and sound level difference about 1dB at each frequency in unoccupied houses.

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A Five-Degree-of-Freedom Room Reverberation Model Based on Objective Measures of Reverberation (잔향의 객관적 평가량에 근거한 5자유도 실내 잔향 모델)

  • 안상태;김양한
    • The Journal of the Acoustical Society of Korea
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    • v.19 no.1
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    • pp.48-53
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    • 2000
  • To analyze a room reverberation, many objective parameters have been suggested as measures of subjective perception in concert hall acoustics. However, it is difficult to understand the relationship among the individual parameters and to have a whole image of them. In this paper five primary objective parameters were selected and a reverberation model based on them was established by the reverberation decay curve. The proposed model was interpreted geometrically in terms of subjective characteristics. And finally we discuss the usefulness and the limitation of the model when it is applied to the analysis and.

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Effect of the Measuring Method of Reverberation Time Using Impulse Response Method on the Normalized Impact Sound Pressure Level (임펄스응답적분법을 이용한 잔향시간의 측정방법이 규준화 바닥충격음레벨에 미치는 영향)

  • Lee, J.W.;Kwon, Y.P.
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.1 s.106
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    • pp.34-39
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    • 2006
  • For the evaluation of the normalized impact sound pressure level, the reverberation time of the receiving room should be measured. This paper deals with the effect of the time constant of FFT analyzer and the measuring points on reverberation time. It is found that the time constant should be in the range between 10 ms and 35 ms. While the effect of measuring points on the reverberation time is significant when the bandwidth is narrow it is negligible in the evaluation of the normalized impact sound pressure level.

A New Method for the Reverberation Time Measurement on Acoustic Rooms (실 음향에서의 잔향 시간 측정 개선에 관한 연구)

  • 이상권;이민성;김봉기
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11b
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    • pp.1104-1108
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    • 2001
  • It is a difficult and important task to measure the reverberation time of an acoustic room with a short reverberation time. This paper presents a new technique to measure the reverberation time of an acoustic room with low value of BT60. The digital signal processing technique used to do this is the wavelet filter which is very flexible to design the 1/n octave band filter and has no delay problem compared with the conventional IIR digital filter. This method is successfully applied to the measurement of the reverberation time at low frequency band of famous concert halls in Korea.

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The accuracy of analyzing reverberation time (잔향 시간 분석의 정확도)

  • Kang, Seong-Hoon;Jung, Han-Kyo
    • The Journal of the Acoustical Society of Korea
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    • v.37 no.5
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    • pp.349-355
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    • 2018
  • A large number of parameters have been defined in order to describe and to evaluate the acoustical propeTies in rooms. Reverberation time is an impoTant characteristic of conceT halls, theaters and studios, etc. Over the years, a number of different methods for measuring the reverberation time have been developed, the most common being: the interrupted noise method, the integrated impulse response method, and the method of recording the room response to an impulsive source. However, the reverberation time can be changed by the measurement method, sound source and microphone. Therefore, it is difficult to accurately measure the reverberation time in a room. In this paper, it will be analyzed the interpretation method of the reverberation time and discussed the limitations.