• Title, Summary, Keyword: Sound Intensity

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A Study on Noise Identification of Compressor Based on Two Dimensional Complex Sound Intensity (Two Dimensional Complex Sound Intensity를 이용한 압축기 소음원 규명에 관한 연구)

  • 안병하;김영수
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.1
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    • pp.83-92
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    • 2000
  • Sound intensity method is well known as a visualization technique of sound field or sound propagation in noise control. Sound intensity or energy flux is a vector quantity which describes the amount and the direction of net flow of acoustic energy at a given position. Especially two dimensional sound intensity method is very useful in evaluating periodic characteristics and acoustic propagation mode of noise source. In this paper, we have studied the noise source Identification, acoustic sound field analysis, and characteristics of noise source of rotary compressor and scroll compressor for air conditioner using complex sound intensity method. Also we proposed a now method of time domain analysis which is used in evaluating of position of noise source in rotary and scroll compressor in this paper This paper presents the advantage, simplicity and economical efficiency of this method by analysing the characteristics of noise source with two dimensional complex sound intensity simultaneously.

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Development and Application of Measuring Method for Instantaneous Intensity (순시 인텐시티 측정 기법의 개발 및 응용)

  • 이장우;안병하
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.960-963
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    • 2003
  • Sound intensity method is well known as a visualization technique of sound field and sound propagation in noise control. Sound intensity is a vector quantity that describes the magnitude and the direction of net flow of acoustic energy at a given position. The current measuring method is expensive and difficult to identify the noise source exactly. In this paper, we have studied the noise source identification and the characteristics of noise source of rotary compressor for air conditioner using complex sound intensity method. The new method for instantaneous sound intensity is also proposed and it is useful for transient state and steady state. The criteria of these state, select auto correlation coefficient. The advantage, simplicity and economic attribution of this method are verified by analyzing the characteristics of noise source with instantaneous sound intensity compared to mean sound intensity.

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Development and Application of Measuring Method of Instantaneous Intensity (순시 인텐시티 측정 기법의 개발 및 응용)

  • 이장우;김영종;안병하;이운섭
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.560-563
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    • 1997
  • Sound intensity method is well known as a visualization technique of sound field and sound propagation in noise control. Sound intensity is a vector quantity that describes the magnitude and the direction of net flow of acoustic energy at a given position. The current measuring method is expensive and difficult to identify the noise source exactly. In this paper, we have studied the noise source identification and the characteristics of noise source of rotary compressor for air conditioner using complex sound intensity method. The new method for instantaneous sound intensity is also proposed and it is useful for transient state and steady state. The criteria of these states select auto correlation coefficient. The advantage, simplicity and economic attribution of this method are verified by analyzing the characteristics of noise source with instantaneous sound intensity compared to mean sound intensity.

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The Estimation of Sound Attenuation Caused by Duct Silencer Using Sound Intensity Method (음향인텐시티법을 이용한 공조 덕트소음기의 감음성능평가방법에 관한 연구)

  • Kim, Seok-Hong;Son, Jang-Yeol;O, Jae-Eung;Kim, Yeo-Sik
    • The Journal of the Acoustical Society of Korea
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    • v.6 no.2
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    • pp.54-61
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    • 1987
  • This paper is to suggest the test method of sound attenuation caused by absorptive duct silencer using sound intensity method in field. In order to estimate sound attenuation, sound power being radiated from sound power source and duct exhaust terminal was measured by the sound pressure method and sound intensity method in semianechoic and common room. The results of the measured sound attenuation values by sound intensity method are more similar to those of theoretical calculation than those by the sound pressure method. In addition, sound intensity method is much less influenced by sound field condition or continuous background noise than the sound pressure method.

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Review of Measurement of Sound Insulation in Buildings and of Building Elements Using Sound Intensity : Laboratory Conditions (Sound Intensity를 이용한 건물부재의 차음성능 실험실 측정방법 고찰)

  • Jung, Sung-Soo;Kook, Chan;Kim, Sun-Woo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1138-1141
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    • 2002
  • In this study, the ISO 15186-1 “Measurement of sound insulation in buildings and of building elements using sound intensity - Part 1 : Laboratory conditions” was reviewed in order to make it as a new Korean Industrial Standard. Several main contents are discussed.

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The Effect of Adaptation to Sound Intensity on the Neural Metabolism in Auditory Pathway: Small Animal PET Study (소동물 [F-18]FDG 양전자단층촬영 기법을 이용한 청각신경에서의 소리크기에 대한 적응효과 연구)

  • Jang, Dong-Pyo
    • Journal of Biomedical Engineering Research
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    • v.32 no.1
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    • pp.55-60
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    • 2011
  • Although sound intensity is considered as one of important factors in auditory processing, its neural mechanism in auditory neurons with limited dynamic range of firing rates is still unclear. In this study, we examined the effect of sound intensity adaptation on the change of glucose metabolism in a rat brain using [F-18] micro positron emission tomography (PET) neuroimaging technique. In the experiment, broadband white noise sound was given for 30 minutes after the [F-18]FDG injection in order to explore the functional adaptation of rat brain into the sound intensity levels. Nine rats were scanned with four different sound intensity levels: 40 dB, 60 dB, 80 dB, 100 dB sound pressure level (SPL) for four weeks. When glucose uptake during the adaptation of a high intensity sound level (100 dB SPL) was compared with that during adaptation to a low intensity level (40 dB SPL) in the experiment, the former induced a greater uptake at bilateral cochlear nucleus, superior olivary complexes and inferior colliculi in the auditory pathway. Expectedly, the metabolic activity in those areas linearly increased as the sound intensity level increased. In contrast, significant decrease interestingly occurred in the bilateral auditory cortices: The activities of auditory cortex proportionally decreased with higher sound intensities. It may reflect that the auditory cortex actively down-regulates neural activities when the sound gets louder.

BASIS RESEARCH ON NOISE CONTROL OF HEAD-FEEDING TYPE COMBINE HARVESTER USING SOUND INTENSITY METHOD

  • Sasao, A.;Iwasa, M.
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • pp.752-760
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    • 1993
  • We research ed on the noise control of a head feeding type combine harvester. It is a kind of combine harvester developed in Japan. And at present, it is used by most Japanese farmer. For a head-feeding type combine harvester it is very difficult to determine the sources of noise because it is a combination of reapers and automatic , threshers and several running parts. However we succeeded in finding out the sound sources of combine harvesters and analyzing their sound by the using sound intensity method. The sound intensity Method is a very up-to-date method to measure and analyze Sound Intensity Levels and sound directions at several measuring point sin a specified area. In this research, first a conventional sound level measurement method is used and secondly the sound intensity method. The first method shows a rather great limitation in allowed exposure duration. The second method shows pin-points the engine itself as being the main source of noise, causing sound flows a ross the operator's seat.

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An Experimental Study of the Application of the Sound-Intensity Technique on the Detection of Defect in Rolling Bearings (굴림 베어링 요소의 결함 검출시 음향 인텐시티기술적용에 관한 실험적 연구)

  • 차경옥
    • Journal of the Korean Society of Marine Engineering
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    • v.23 no.4
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    • pp.473-479
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    • 1999
  • The two-microphone sound-intensity technique has been used for the detection of defects in ra-ally loaded ball bearings. The difference in the sound-intensity levels measured for bearings with no defect and for those with intentionally introduced defects of different sizes n heir elements under various operating conditions of loads and speeds is demonstrated. The results show that of an inner-race or ball defect. It is difficult to detect defects at lower speeds. Sound-pressure measurements were also performed for comparison and it shown that the detectability of defects by sound-intensity measurements is better than that by sound-pressure measurements.

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APPLICATION OF SOUND INTENSITY METHOD TO NOISE CONTROL ENGINEERING AND BUILDING ACOUSTICS

  • Tachibana, Hideki
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.7-15
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    • 1995
  • Sound pressure and particle velocity are the most essential quantities prescribing a sound field; they correspond to voltage and electric current respectively, in electric system. As electric power is the product of voltage and electric current, sound intensity is the product of sound pressure and particle velocity and it means the acoustic power passing through a unit area in a sound field. Although the definition of sound intensity is very simple as mentioned above, the method of measuring this quantity has not been realized for a long time, because it has been very difficult to measure the particle velocity simultaneously with the sound pressure. Owing to the recent development of such technologies as transducer production and digital signal processing, it has finally been realized. According to the sound intensity(SI) method, the sound power flow in an arbitrary sound field can be directly measured as a vector quantify. In this paper, the principle of the SI method is briefly explained at first and some examples of its application made in the author's laboratory are introduced.

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Active Control of External Noise Radiated From Duct Using Sound Intensity (음향 인텐시티를 이용한 관 외부 방사 소음의 능동 제어)

  • 강성우;김양한
    • Journal of KSNVE
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    • v.7 no.3
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    • pp.427-437
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    • 1997
  • Mean active intensity based active control for the cancellation of radiated noise out of the duct exit is studied. The active intensity control strategy is drerived based on the relation of the exterior sound field out of the duct termination and interior sound field of the duct. One of the characteristics of this control strategy is that the control performance can be maintained regardless of the sensor loction, compared with the conventional local pressure control methods at either interior downstream or exterior field positions. It is also suggested that the digital filtering for the active intensity control can be achieved by time-domain filtered-x LMP (Lest-Mean-Product) adaptive algorithm. Experiments for an open-ended duct are performed to compare the active intensity control performance with conventional pressure control one. Active control experiment of local sound pressure is conducted by widely used filtered-x LMS adaptive Algorithm and active intensity control implementaion uses the derived filter d-x LMP algorithm. It is shown that the exterior sound fileds was much better observable by sensing of the active intensity than by just sound pressure. It is also demonstrated that the global control performance of external field by acoustic intensity is superior to the conventional sound pressure control performance.

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