• Title/Summary/Keyword: Reverberation room

Search Result 153, Processing Time 0.022 seconds

Sound transmission loss measurement of railway vehicle floor using semi-reverberation room (간이잔향실을 이용한 철도차량 바닥재의 음향투과손실 측정)

  • Shin, Bum-Sik;Chun, Kwang-Wook;Choi, Yeon-Sun
    • Proceedings of the KSR Conference
    • /
    • 2008.11b
    • /
    • pp.1420-1425
    • /
    • 2008
  • This study is to examine the sound transmission loss of a railway vehicle floor. To this end, a semi-reverberation room was constructed. The semi-reverberation room was made of a railway vehicle floor between the sound radiating chamber and the sound receiving chamber. To block the sound, the wall was made of acryl, urethane foam, wood, and glass fiber. The test followed the KS F 2808 standard, and a typical reverberation room was used to verify the performance of the semi-reverberation room. As a result, comparison of the measurements showed that the test results of the semi-reverberation room had the same tendency as those of the reverberation room. Consequently it was possible to measure the sound transmission loss of railway vehicle structures using the semi-reverberation room.

  • PDF

A Study on the Reverberation Time Characteristics of Inside Space of Apartment Buildings (공동주택 내부 공간의 잔향시간 특성 조사 연구)

  • Jeong, Jeong Ho;Lee, Byung Kwon;Jeon, Jin Yong
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.25 no.4
    • /
    • pp.291-298
    • /
    • 2015
  • In this study, the reverberation time of apartment living room was measured and distribution of the reverberation time was analyzed. In addition, sound field characteristics of mock-up test room similar with living room and timber structured bedroom was investigated with addition of furniture and sound absorption material. Average reverberation time of unfurnished apartment unit was 1.11 s, and reverberation time in 630 Hz~2000 Hz bands were longer than 1.2 s. It was found that from the field measurement results, reverberation time characteristic of furnished apartment living room was uniform in most of frequency bands. Averaged reverberation time of furnished living room was 0.48 s and the reverberation time of bedroom was 0.44 s. Standardized sound pressure level correction values were calculated from the average reverberation time of furnished and unfurnished apartment units. The correction value of unfurnished living room was −3.4 dB and that of furnished living room was 0.2 dB. Measured reverberation time of furnished and unfurnished apartment units indicated that reference reverberation time; 0.5 s, in KS and ISO standards is reasonable also in Korean residential environment.

Measurement of Short Reverberation Times at Low Frequencies Using Wavelet Filter Bank

  • Lee, Sang-Kwon
    • Journal of Mechanical Science and Technology
    • /
    • v.17 no.4
    • /
    • pp.511-520
    • /
    • 2003
  • In room acoustics, reverberation time is an important acoustic parameter. However it is often difficult to measure short reverberation times at low frequencies with a traditional band pass filter bank if the product of filter bandwidth (B) and reverberation time (T) is small. It it well known that the minimum permissible product of bandwidth and reverberation time of the traditional band pass filter is at least 16. This strict requirement makes it difficult to measure short reverberation times of an acoustic room at low frequencies exactly. In order to reduce this strict requirement, in the previous paper, the wavelet filter bank was developed and the minimum permissible product of bandwidth and reverberation time was replaced with 4. In the present paper it is demonstrated how the short reverberation times of an practical room at low frequencies are successfully measured by using the wavelet filter bank and the results are compared with the traditional method using a band past filer bank.

Measurement of Short Reverberation Times of an Acoustic Room at Low Frequencies Using Wavelet Transform (웨이브렛 변환을 이용한 저주파에서 짧은 잔향 시간을 갖는 실음향에서의 잔향시간 측정에 관한 연구)

  • 이상권
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2002.05a
    • /
    • pp.1077-1080
    • /
    • 2002
  • In building acoustics, reverberation time is an important acoustic parameter. However, it is often difficult to measure short reverberation times at low frequencies using the traditional band pass filter bank if the product of bandwidth (B) and reverberation time (T) is small. It is well known that the minimum permissible product of bandwidth and reverberation time of the traditional band pass filter is at least 16 [F. Jacobsen, J. Sound Vib. 115, 163-170 (1987)]. This strict requirement makes it difficult to measure short reverberation times of an acoustic room at low frequencies exactly. In order to reduce this strict requirement, recently, the wavelet filter bank is developed and the minimum permissible product of bandwidth and reverberation time is replaced with 4 [S. K. Lee, J, Sound Vib. 252, 141-153 (2002)]. In the present paper, it is demonstrated how the short reverberation times at low frequencies are successfully measured by using the wavelet filter bank. In order to present this job, two synthetic signals and one measured signal are used for impulse responses of an acoustic room.

  • PDF

Investigation of the Indoor Noise of Naval Vessel according to the Sound Absorption and Reverberation Time in a Cabin (함정 격실에 적용되는 흡음재와 잔향시간에 따른 실내 소음 분석)

  • Han, Hyung-Suk;Park, Mi-Yoo;Cho, Heung-Gi;Kim, Joong-Gil;Im, Dong-Been;Son, Yoon-Jun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2010.10a
    • /
    • pp.586-591
    • /
    • 2010
  • The sound field can be classified to the direct and reverberant sound field. If the sound absorption material in a room is not applied sufficiently, the reverberant sound field increases and the sound pressure in a room also increases when the sound source exists in a room. Therefore, the reverberation time should be controled in order to reduce the reverberant sound as well as sound pressure level in a room. Even though the reverberation time is specified and researched widely in architectural engineering, it is rarely performed in a marine engineering. Therefore, in this research, the reverberation time in a navel vessel is researched related to the noise reduction in a cabin.

  • PDF

Evaluation on Acoustic Performance of the DICT's Acoustic Loboratory (대우건설기술연구소 음향실험동의 성능 평가)

  • 정갑철;이주원;윤창연;박칠림
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 1998.04a
    • /
    • pp.735-740
    • /
    • 1998
  • Acoustic performance of DICT's acoustic laboratory was evaluated. As a result, background noise and inverse squre law of an anechoic room were satisfied with ISO 3745 standard value. Also, reverberation time and standard deviation of sound pressure level distribution in reverberation rooms were within maximum error limit that was ruled on ISO 3741.

  • PDF

Subjective Evaluation of Stage Acoustics with the alteration of the sound pressure level of reverberation. (잔향음압의 변화에 대한 무대음향의 주관적 평가)

  • Kim, Young-Sun;Jeong, Jeong-Ho;Jeon, Jin-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2003.11a
    • /
    • pp.742-742
    • /
    • 2003
  • This study is about the effect of the sound pressure level of reverberation on stage acoustics. There are several electro-acoustics systems to enhance the room acoustics of concert hails but not many studies on the stage acoustics for the musicians who plays on the stages. To investigate the effect of reverberation on stage acoustics, the reverberation time of a test room has been controlled through a 4 channel speaker system, and the preferred reverberation level has been selected by performing musicians. As a result, the sound pressure level of reverberation seems to affect the perception of stage acoustics which motivates musicians' performances.

  • PDF

Investigation of the Indoor Noise of Naval Vessel with Regarding to the Sound Absorption and Reverberation Time in a Cabin (함정 격실에 적용되는 흡음재와 잔향시간에 따른 실내 소음 분석)

  • Han, Hyung-Suk;Park, Mi-Yoo;Cho, Heung-Gi;Kim, Joong-Gil;Im, Dong-Been;Son, Yoon-Jun
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.20 no.10
    • /
    • pp.960-967
    • /
    • 2010
  • The sound field can be classified to the direct, diffract and reverberant sound field. If the sound absorption material in a room is not applied sufficiently, the reverberant sound field increases and the sound pressure in a room also increases when the sound source exists in a room. Therefore, the reverberation time should be controled in order to reduce the reverberant sound as well as sound pressure level in a room. Even though the reverberation time is specified and researched widely in architectural engineering, it is rarely performed in a marine engineering. Therefore, in this research, the reverberation time in a navel vessel is researched related to the noise reduction in a cabin.

The effect of diffusers on the measurement of sound absorption in a reverberation room (잔향실법 흡음률 측정에 미치는 확산체의 영향)

  • Han, Hee-Kab;Kim, Kyung-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2006.05a
    • /
    • pp.1194-1197
    • /
    • 2006
  • Recently, international standard for measurement of sound absorption in a reverberation room has been amended. In the revised version, temperature, humidity and air pressure conditions are strictly restricted and also the concrete procedures are presented to reduce the differences in test results by adding inspection of diffusion, measurement uncertainty etc. In this paper, the systematic tests are conducted based on the inspection guide of diffusion defined by ISO 354 and the effects of diffusers on the measurement of sound absorption ratio are considered. As a result, we perceived that the averaged sound absorption ratio in mid and high frequency range is expected to measure around $0.05{\sim}0.1$ higher in high sound absorption material. Therefore, as for the reverberation room for measurement of sound absorption, we need to take into consideration not only the spatial standard deviation of sound pressure mandated by ISO 3741, but also, inspection regulation of diffusion showed by ISO 354.

  • PDF

An Experimental Study on the Prediction Method of Light Weight Floor Impact Sound Insulation Performance of Apartment Floor Structures through Mini-Laboratory Tests (축소실험실을 이용한 바닥완충구조의 경량충격음 차음성능 예측방법에 관한 실험적 연구)

  • 송민정;장길수;김선우
    • Journal of KSNVE
    • /
    • v.10 no.1
    • /
    • pp.82-96
    • /
    • 2000
  • The purpose of this study is to figure out the relationship between the mini-laboratory and the reverberation room for the domestic floor structures which are practically constructed in apartment houses. For this purpose, seven specimen which were varied in structures and thicknesses were tested in Chonnam National University reverberation room and in the artificial mini-laboratory which is the $\farc{1}{3}$ scale model of the former. From the result of this study, it was proved that there is a good correlation between the mini-laboratory and the reverberation room for the apartment floor structures as well as floorcovering PVC. The result of this study could save the labor and the time, etc.

  • PDF