• Title/Summary/Keyword: Reverberation level

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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
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    • 2003.11a
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    • pp.742-742
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    • 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.

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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.

Experimental Study on Source Level Estimation Techniques of Underwater Sound Source in Reverberant Water Tank (잔향수조 내 수중음원의 음원레벨 추정기법에 관한 실험연구)

  • Kim, Kookhyun
    • Journal of Ocean Engineering and Technology
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    • v.33 no.4
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    • pp.358-363
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    • 2019
  • The acoustic power is used as a primary index characterizing underwater sound sources and could be defined by its source level. The source level has been assessed using various experimental techniques such as the reverberation time method and reverberant tank plot method. While the reverberation time method requires reverberation time data extracted in a preliminary experiment in a reverberant water tank, the reverberant tank plot method only needs acoustic pressure data directly obtained at the reverberation water tank. In this research, these experimental techniques were studied in comparative experiments to estimate the source levels of underwater sources in a reverberant water tank. This paper summarizes the basic theories and procedures of these experimental techniques and presents the experimental results for an underwater source in a long cuboid water tank using each technique, along with a discussion.

Bi-static Low-frequency Reverberation Model in Shallow Water (천해 저주파 양상태 잔향음 모델)

  • 김남수;오선택;윤관섭;이성욱;나정열
    • The Journal of the Acoustical Society of Korea
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    • v.22 no.6
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    • pp.472-481
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    • 2003
  • Low-frequency hi-static reverberation model (LHYREV-B, Low-frequency Hanyang univ. Reverberation model-Bistatic) based on the parabolic approximation for shallow water environment is presented. In this paper bistatic reverberation level is computed using the angle-independent scattering strength function and the wave-based acoustic model. The signal simulated by the LHYREV-B model is compared with the observed signals and it is shown that the LHYREV-B model provides a closer fit to the observed signals.

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
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    • v.25 no.4
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    • pp.291-298
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    • 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.

The Noise Measurement Method of the Multi-Sound Source in Reverberation Field wiht Wave-Guide (Reverberation 음장내 다수 소음원의 음파관을 이용한 소음 측정 방법)

  • 이성태
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1996.04a
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    • pp.275-285
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    • 1996
  • A noise measurement method of the multi-sound sources in a reverberation field with wave-guide is developed by experimental method. In the reverberation field, it is very hard to measure sound level or noise spectra of a certain sound source, when many sound sources generate noise simultaneously with a small space between them. Flexible wave-guide(tube) was used to measure noise level in a reverberation field. One end of the tube is attached to a sound source and the other end is closed with an anechoic terminal. Detailed method of the measurement and the source of error was considered as well.

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Effects of the Shape and the Absorption in Reverberation Rooms on the Space Variances of the Sound Pressure Level (잔향실의 형상(치수비)과 내부표면 흡음율이 음압의 공간편차에 미치는 영향)

  • 최석주;장영자
    • The Journal of the Acoustical Society of Korea
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    • v.18 no.4
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    • pp.65-70
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    • 1999
  • To examine the space variances of the sound pressure level for five different types (normal frequency spacing) of reverberation rooms, simulations were conducted using the Finite Element Method. In case of infinite surface impedance, nonrectangular reverberation rooms showed small Standard Deviations across the band of frequency, and in case of finite surface impedance, ideal rectangular reverberation rooms showed the similar results as those in irregular shaped reverberation rooms.

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Bistatic reverberation simulation using intersection of scattering cross section between sound source and receiver (음원과 수신기 사이에 교차 산란단면적을 이용한 양상태 잔향음 모의)

  • Oh, Raegeun;Kim, Sunhyo;Son, Su-Uk;Choi, Jee Woong;Park, Joung-Soo;Shin, Changhong;Ahn, Myonghwan;Lee, Bum Jik
    • The Journal of the Acoustical Society of Korea
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    • v.36 no.1
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    • pp.12-22
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    • 2017
  • It is important to predict accurately reverberation level, which is a limiting factor in underwater target detection. Recently, the studies have been expanded from monostatic sonar to bistatic sonar in which source and receivers are separated. To simulate the bistatic reverberation level, the computation processes for propagation, scattering strength, and scattering cross section are different from those in monostatic case and more complex computation processes are required. Although there have been many researches for bistatic reverberation, few studies have assessed the bistatic scattering cross section which is a key factor in simulate reverberation level. In this paper, a new method to estimate the bistatic scattering cross section is suggested, which uses the area of intersection between two circles. Finally, the reverberation levels simulated with the scattering cross section estimated using the method suggested in this paper are compared with those estimated using the methods previously suggested and those measured from an acoustic measurements conducted in May 2013.

Floor Impact Sound Pressure Level Characteristics by the Change of Reverberation Time in a Reverberation Chamber (수음실 잔향 시간변화에 따른 바닥충격음레벨 특성 - 잔향실을 중심으로 -)

  • Jeong, Jeong Ho;Kim, Jeong Uk;Jeong, Jae Gun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.3
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    • pp.274-281
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    • 2013
  • Field measurement method of heavy/soft impact sound pressure level which is regulated in JIS and ISO has been using in Korea, Japan and Canada. It is reported that heavy/soft impact sound pressure level was varied by the sound field condition of receiving room such as sound absorption power and room volume. In this study, it is checked that heavy/soft impact sound pressure level was affected by the receiving sound field condition. Rubber ball and bang machine sound pressure level was measured in the vertically connected reverberation chamber. In oder to check the effect of receiving sound field on heavy/soft impact sound pressure, sound absorption power was changed with polyester sound absorption blankets with air space and glass wool. The reverberation time at 1 kHz band was changed from 10 s to 0.2 s by sound absorption material. Rubber ball sound pressure level measured without sound absorption material was 58 dB in $L_{i,Fmax,AW}$, but the level was 46 dB with sound absorption treatment. From this result, it is confirmed that sound field correction method is needed in the heavy/soft impact sound pressure level measurement method using bang machine and rubber ball.

Simulation of underwater reverberation signals (수중 잔향음 신호 모의)

  • Oh, Sun-Taek;Na, Jung-Yul
    • The Journal of the Acoustical Society of Korea
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    • v.13 no.6
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    • pp.66-74
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    • 1994
  • Simulation of sonar reverberation time series is very useful because most acoustic models are power level models and have a difficulty when performance of hardware system is evaluated under the reverberant condition. Thus, in this paper, the simulation of reverberation time series is attempted, First, normalized spectrum, whose bandwidth is varying in the frequency domain and which has zero-mean Gaussian distribution, is calculated at pre-selected receiving time. Second, reverberation levels given by underwater acoustic model are combined with normalized spectrum in the frequency domain. Finally, nonstationary sonar reverberation time series are simulated by IFT(Inverse Fourier Transform).

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