• Title/Summary/Keyword: Reverberation room

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Performance Improvement of Stereo Acoustic Echo Canceller Using MINT Filtering (MINT 필터링에 의한 스테레오 음향 반향 제거기의 성능 향상)

  • 차경환
    • The Journal of the Acoustical Society of Korea
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    • v.21 no.1
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    • pp.42-46
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    • 2002
  • In this paper, a new pre-processing algorithm is proposed to improve the performance of stereo acoustic echo canceller. The proposed algorithm has the improved performance by the estimation error reduction of filter coefficient using input signal which was reduced reverberation of room in the basis MINT (Mu1tip1e-input/output Inverse Theorem) filtering. For real stereo speech signal and real room impulse response the results of simulation, we showed that the proposed method could improved 3∼5 dB ERLE (Echo Return Loss Enhancement) regardless of NLMS (Normalized Least Mean Square) and Projection adaptive algorithm.

Sound Power Measurements Based on ISO 3741 and 3745

  • Lee, Kang-Il;Kim, Hyun-Tae;Yoon, Suk-Wang
    • The Journal of the Acoustical Society of Korea
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    • v.19 no.1E
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    • pp.13-21
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    • 2000
  • In this paper, we present the description and results of experimental study of the sound power measurements based on International Standards ISO 3741 and 3745. The sound power emitted by a calibrated reference sound source was measured in a reverberation room and a free field over a reflecting plane, using the precision methods of International Standards ISO 3741 direct method and ISO 3745, respectively. The sound power measurements carried out in this study give accurate estimation and also show that both methods for determining the sound power levels of a sound source in a reverberation room and a free field over a reflecting plane, according to the ISO 3741 and 3745, respectively, have proved equally good.

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Measurement of the Reverberation Time of Rooms with Reference to Other Acoustical Parameters (실의 잔향시간 측정방법 고찰)

  • 오양기;주진수;정광용;김선우
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.230-233
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    • 2001
  • Revision of KS, Korean Standards, is currently actively discussed. It is just the time for a new world class standards under the new system with WTO, World Trade Organization. This paper is a part of "Researches on the Standards in the Building Acoustic Field", as one of KS revision projects. The aim of this study is to define the requirements for measuring the reverberation time of rooms with reference to other acoustical parameters. In the former KS, there is no items matched with this purpose. Therefore measuring reverberation time and other room acoustical parameters with confidential test procedure was impossible. On these basis, a new part of KS is proposed, and some problems remained and further discussions in the proposed draft are described in this study.

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Development of a Practical Two-Microphone Impedance Tube Method for Sound Transmission Loss Measurement of Sound Isolation Materials

  • Ro, Sing-Nam;Hwang, Yoon;Lee, Dong-Hoon
    • International Journal of Air-Conditioning and Refrigeration
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    • v.11 no.3
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    • pp.105-113
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    • 2003
  • This study developed a practical two-microphone impedance tube method to measure the sound transmission loss of sound isolation materials without the use of an expensive reverberation room or an acoustic intensity probe. In order to evaluate the validation and applicability of the two-microphone impedance tube method, sound transmission losses for several sound isolation materials with different surface density and bending stiffness were measured, and the measured values were compared with the results from the reverberation room method and the theory. From the experimental results, it was found that the accuracy of sound transmission loss obtained by the impedance tube method depends upon the diameter size of the impedance tube (i.e., tested sample size). For sound isolation materials having relatively large bending stiffness such as acryl, wood, and aluminum plates, it was found that the impedance tube method proposed by this study was not valid to measure the sound transmission loss. On the other hand, for sound isolation materials having relatively small bending stiffness such as rubber, polyvinyl, and asphalt sheets, the comparisons of transmission loss between the results from the impedance tube method and the theory showed a good agreement within the range of the frequencies satisfying the normal incidence mass law. Therefore, the two-microphone impedance tube method proposed by this study can be an effective measurement method to evaluate the sound transmission loss for soft sound isolation sheets having relatively small bending stiffness.

Speech Quality Estimation Algorithm using a Harmonic Modeling of Reverberant Signals (반향 음성 신호의 하모닉 모델링을 이용한 음질 예측 알고리즘)

  • Yang, Jae-Mo;Kang, Hong-Goo
    • Journal of Broadcast Engineering
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    • v.18 no.6
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    • pp.919-926
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    • 2013
  • The acoustic signal from a distance sound source in an enclosed space often produces reverberant sound that varies depending on room impulse response. The estimation of the level of reverberation or the quality of the observed signal is important because it provides valuable information on the condition of system operating environment. It is also useful for designing a dereverberation system. This paper proposes a speech quality estimation method based on the harmonicity of received signal, a unique characteristic of voiced speech. At first, we show that the harmonic signal modeling to a reverberant signal is reasonable. Then, the ratio between the harmonically modeled signal and the estimated non-harmonic signal is used as a measure of standard room acoustical parameter, which is related to speech clarity. Experimental results show that the proposed method successfully estimates speech quality when the reverberation time varies from 0.2s to 1.0s. Finally, we confirm the superiority of the proposed method in both background noise and reverberant environments.

Sound Transmission Loss Measurement for Sound Isolation Sheets by Two-Microphone Impedance Tube Method (두 개의 마이크로폰의 부착된 임피던스관법을 이용한 차음시트의 음향투과손실 측정)

  • Lee, Dong-Hoon;Yong, Ho-Taek;Lee, Seung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.1
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    • pp.63-72
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    • 2002
  • The main objective of this study is to propose a practical two-microphone impedance tube method to measure the sound transmission loss for flexible sound isolation sheets without the use of the time-consuming and expensive reverberation room. This method was based on the sound decomposition theory developed by Seybert using the spectral density functions of the incident and reflected sound waves. In order to verify the validity of the experimental results, the measured sound transmission losses from the proposed method were compared with the measured data from the reverberation room method and the calculated data from the theory satisfying the mass law of sound isolation material. The resulted trends of the sound transmission losses versus frequencies for several different sound isolation sheets were almost same for each other and agreed quite well in both methods except at some low frequency region. From the experimental results, it was found that the accuracy of sound isolation capability obtained by two-microphone impedance tube method depends upon the microphone spacing, the distance from the first microphone to the test sample surface and the test sample location.

An Study on the Improvement of Acoustics Performance of the Lecture Room (대학 강의실의 음향성능 개선에 관한 연구)

  • Han, Kyeong-Yeon;Seo, Jung-Seok;Kim, Jae-Soo
    • Proceeding of Spring/Autumn Annual Conference of KHA
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    • 2004.11a
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    • pp.361-366
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    • 2004
  • This study has carried out in order to furnish the fundamental material to systemize the lecture room into multimedia in the future, by locating college lecture room as the subject of study, by compare and analyze on acoustic character in both before and after of each improvement. Thereby, now we are about to compare and analyze on physical character of room acoustics in both common lecture room before improvement and the modified multimedia-lecture room after its improvement. Observing the conclusion obtained through experiment, reverberation time in the modified 'lecture room after improvement' became shorter compare with the 'lecture room before improvement', definition and RASTI also improved to be suitable to lecture, and considered that it is able to elevate the intimacy with studying and teaching efficiency, as well.

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A Study on the Power Level Measurement and Evaluating Vocabulary of H.D. TV Sets -Focused on LCD·PDP Tv Sets- (고화질 TV Set의 음향 파워 레벨 측정 및 평가 어휘 선정에 관한 실험적 연구 - LCD·PDP TV Set를 중심으로 -)

  • Lee, Tai-Gang;Park, Hyeon-Ku;Lee, Ju-Yeob;Lee, Jai-Cheon;Shin, Jong-Keun;Kim, Hye-Jin;Kim, Sun-Woo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.9 s.102
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    • pp.1092-1099
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    • 2005
  • This experimental study deals with the characteristics of LCD or PDP TV set noise, which are differ form those of CRT TV set. These characteristics are most important for establishing the effective method to reduce noise level, searching for the appropriate exposure level and evaluation method of LCD or PDP TV set noise. This study adopt two measurement method to specify the power level of LCD or PDP TV set noise in anechoic room(ISO 3741) and reverberation room(ISO 3745) . Comparing with each results of the two method, the reverberation room method is more simple in measuring and calculating the power level. And the subjective response test are carried out to select the pair of appropriate adjectives to present the characteristics of LCD or PDP TV set noise. The pair of 17 adjectives are selected from the 168 adjectives which are used in presenting the sound and noise form literature.

Performance Enhancement of Speech Communication System using Reverberation Rejection (잔향제거를 이용한 음성통신 시스템 성능 향상)

  • Kim, Se-Young;Kang, Suk-Youb;Kim, Ki-Man
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.13 no.10
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    • pp.2211-2217
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    • 2009
  • In this paper, we propose the speech enhancement algorithm using an one-microphone in a reverberant room environments. Spectral subtraction is the effective method which can reduce the reverberation element and the noise in a spectrum domain. Spectral subtraction needs correct separation of voice section and silent section therefore to improve the performance, voice activity detection(VAD) based on entropy has been applied to the proposed method. We test a performance of the proposed method by comparing with conventional method which used VAD based on energy detection. Reverberation reduction ratio with variable of SNR and a reverberation time is used as a test index. From the simulation result, proposed method shows performance better than conventional method.