• Title/Summary/Keyword: Sound parameters

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DEVELOPMENT OF A SOUND QUALITY INDEX FOR THE EVALUATION OF BOOMING NOISE OF A PASSENGER CAR BASED ON REGRESSIVE CORRELATION

  • LEE J. K.;PARK Y. W.;CHAI J. B.;JANG H. K.
    • International Journal of Automotive Technology
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    • v.6 no.4
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    • pp.367-374
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    • 2005
  • This paper proposes a sound quality index to evaluate the vehicle interior noise. The index was developed using a correlation analysis of an objective measurement and a subjective evaluation data. First, the objective set of measurements was obtained at two specified driving conditions. One is from a wide-open test condition and the other is from a constant-speed test condition. At the same time, subjective evaluation was carried out using a score of ten scale where 17 test engineers participated in the experiment. The correlation analysis between the psycho-acoustic parameters derived from the objective measurement and the subjective evaluation was performed. The most critical factors at both test conditions were determined, and the corresponding equations for the sound quality were obtained from the multiple factor regression method. Finally, a comparative work between previous index and present index was performed to validate the effectiveness of the proposed index.

Development of a Sound Quality Index for the Evaluation of an Intake Noise of a Passenger Car (급가속시 차량의 흡기소음에 대한 음질지수 개발)

  • Lee, J.K.;Park, Y.W.;Chai, J.B.
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.8 s.101
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    • pp.939-944
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    • 2005
  • In this paper, a sound quality index for the evaluation of the vehicle intake noise was developed through a correlation analysis of the objective measurement and the subjective evaluation. First, intake orifice noise was measured at the wide-open throttle sweep condition. And then, the acoustic transfer function between intake orifice noise and interior noise was measured. Simultaneously, subjective evaluation was carried out with a 10-scale score by 8 special engineers. The correlation analysis between the psychoacoustic parameters derived from the measurement and the subjective evaluation was performed. The most critical factor was determined and the corresponding sound quality index for intake noise was obtained from the multiple factor regression analysis method. Finally, the effectiveness of the proposed index was validated.

Implementation of ray tracing simulator for extracting sound field parameters (음장파라미터 추출을 위한 음선추적 시뮬레이터의 구현)

  • Lee, Deok-Su;Seong, Goeng-Mo
    • The Journal of the Acoustical Society of Korea
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    • v.14 no.3
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    • pp.82-89
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    • 1995
  • A sound field simulator is constructed to obtain the sound field paramaters such as the magnitudes and directions of early reflections with moderate efforts. The proposed simulator is based on the hybrid ray tracing method that traces rays reached the listener position and convert them to image sound sources. By this approach, we can obtain the directional impulse response relatively easily with minimum casts. Simulation experiment results of several performace places are reported to how the versatility of the proposed simulator system.

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Vibro-acoustic analysis of un-baffled curved composite panels with experimental validation

  • Sharma, Nitin;Mahapatra, Trupti R.;Panda, Subrata K.
    • Structural Engineering and Mechanics
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    • v.64 no.1
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    • pp.93-107
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    • 2017
  • The article presents the vibration and acoustic responses of un-baffled doubly curved laminated composite panel structure under the excitation of a harmonic point load. The structural responses are obtained using a simulation model via ANSYS including the effect various geometries (cylindrical, elliptical, spherical and hyperboloid). Initially, the model has been established by solving adequate number of available examples to show the convergence and comparison behaviour of the natural frequencies. Further, the acoustic responses are obtained using an indirect boundary element approach for the coupled fluid-structure analysis in LMS Virtual.lab by importing the natural frequency values. Subsequently, the values for the sound power level are computed using the present numerical model and compared with that of the available published results and in-house experimentally obtained data. Further, the acoustic responses (mean-square velocity, radiation efficiency and sound power level) of the doubly curved layered structures are evaluated using the current simulation model via several numerical experimentations for different structural parameters and corresponding discussions are provided in detail.

Interior Noise Reduction of Enclosure Using Predicted Characteristics of Absorber (흡음재의 음향특성 예측에 의한 밀폐계의 내부 소음저감)

  • Lee Ghi-Youn;Sim Hyoun-Jin;Lee Jung-Yoon;Oh Jae-Eung
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.4 s.181
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    • pp.60-66
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    • 2006
  • For the purpose of finding out the sound field characteristics in a rectangular cavity, analytical and experimental studies are performed with white noise input. Two-microphone impedance tube method is used to measure the impedances of foamed aluminum. Foamed aluminum is well known metallic porous material which has excellent properties of light weight and high absorbing performance. And predicted impedances of foamed aluminum are compared with measured impedances. The predicted acoustical parameters are applied to the theoretical analysis to predict sound pressure field in the cavity. The measured sound absorption effects are compared with the predicted values for both cases with and without foamed aluminum lining in the cavity of the rectangular enclosure.

A Study on the Improvement of Reverberation Room's Performance (잔향실 성능 검증 및 향상 연구)

  • Kim, Sung-Hoon;Joo, Won-Ho;Kim, Dong-Hae;Bae, Jong-Guk
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.171-175
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    • 2006
  • Recently, two reverberation rooms were built up of 300mm thick concrete walls in non-parallel pentagonal shape to measure the sound absorption, transmission, radiation, and impact insulation of acoustical materials, panels, doors, etc. Various acoustic tests, including the sound transmission test, were carried out to investigate their acoustic performances. In order to improve the performance, several modifications on these acoustical parameters, such as the acoustic mode, the position of specimen, the formation of diffuse field, the location of sound source, and flanking transmission, have been conducted. Through a series of tests, the reverberation rooms have been effectively improved so that it could perform a variety of acoustic tests with the international standard. And then, it is expected to be very helpful in developing the low noise design technology for ships.

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Computation of Sound Radiation in an AxisymmetricSupersonic Jet

  • Kim, Yong-Seok;Lee, Duck-Joo
    • International Journal of Aeronautical and Space Sciences
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    • v.5 no.2
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    • pp.18-27
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    • 2004
  • An axisymmetric supersonic jet is simulated at a Mach number 2.1 and a Reynolds numberof 70000 to identify the mechanism of Mach wave generation and radiation from the jet. In orderto provide the near-field radiated sound directly and resolve the large-scale vortices highly.high-resolution essentially non-oscillatory(ENO) scheme, which is one of the ComputationalAeroAcoustics(CAA) techniques, is newly employed. Perfectly expanded supersonic jet is selectedas a target to see pure shear layer growth and Mach wave radiation without effect of change injet cross section due to expansion or shock wave generated at nozzle exit. The sound field ishighly directional and dominated by Mach waves generated near the end of potential core. Thenear field sound pressure levels as well as the aerodynamic properties of the jet, such asmean-flow parameters are in fare agreement with experimental data.

Variations in the perception of lexical pitch accents and the correlations with individuals' autistic traits

  • Lee, Hyunjung
    • Phonetics and Speech Sciences
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    • v.9 no.2
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    • pp.53-59
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    • 2017
  • The present study examined if individual listeners' perceptual variations were associated with their cognitive characteristics indexed by the Autistic Spectrum Quotient (AQ). This study first investigated the perception of the lexical pitch accent contrast in the Kyungsang Korean currently undergoing a sound change, and then tested if listeners' perceptual variations were correlated with their AQ scores. Eighteen Kyungsang listeners in their 20s participated in the perception experiment where they identified two contrastive accent words for auditory stimuli systematically varying F0 scaling and timing properties; the participants then completed the AQ questionnaire. In the results, the acoustic parameters reporting reduced phonetic differences across accent contrasts for younger Kyungsang generation played a reliable role in perceiving the HH word from HL, suggesting the discrepancy between the perception and the production in the context of sound change. This study also observed that individuals' perceptual variations were negatively correlated with their AQ sub scores. The present findings suggested that the sound change might appear differently between production and perception with a different time course, and deviant percepts could be explained by individuals' cognitive measure.

Analysis of the Room Acoustic Characteristics depending on the Sound Sources for a Multi-purpose Gymnasium finished with Absorbers on Walls and Ceiling (벽 및 천장이 흡음재로 마감된 다목적 체육관에서 음원종류에 따른 실내음향특성의 분석)

  • Park, Hyeon-Ku;Jeon, Ji-Hyun;Song, Hyuk;Kim, Sun-Woo
    • KIEAE Journal
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    • v.2 no.1
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    • pp.41-48
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    • 2002
  • This study aims to investigate and evaluate the room acoustic designs of a multi purpose gymnasiums which do not use adjustable treatments in order to change the acoustical characteristics. Considering the main uses of gymnasium and auditorium, experiments were carried out using both nondirectional speakers on the stage and loudspeaker installed on the ceiling. The result from the study are as follows; Measured RT under unoccupied condition was a little longer than the expected value, therefore, in the case of occupied condition RT would be close to the optimum value. However, parameters that evaluate intelligibility and speech transmission property appeared to be low and have large differences depending on the measuring points, therefore, more effective sound reflecting surfaces and sound reinforcement systems should be considered.

The Design Analysis for the Reduction of Radiated Sound from the Motor-die in Washing Machine (세탁기 모터다이의 방사음 저감을 위한 설계해석)

  • 서대원;홍정혁;오재응
    • Journal of KSNVE
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    • v.9 no.2
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    • pp.371-376
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    • 1999
  • The purpose of this study is to identify the dynamic characteristics of a motor-die in washing machine and provide quantitative design information needed for reduction of radiated sound from the motor-die. To perform the design analysis, dynamic characteristics are identified by motor-die modeling and the availability of model is verified by experimental modal analysis. Numerical approach using MSC/NASTRAN and SYSNOISE predicted sound attenuation effects according to the change of design parameters, such as thickness, concentrated mass and rib. The numerical results due to the rib attachment showed the significant noise attenuation effects over 15 dB in the frequency range of 450∼700 Hz.

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