Main text The key comparison CCAUV.A-K6 has been carried out under the auspices of the Consultati... more Main text The key comparison CCAUV.A-K6 has been carried out under the auspices of the Consultative Committee on Acoustics, Ultrasound and Vibration (CCAUV) of the International Committee of Weights and Measures (CIPM). This comparison is concerned with primary pressure calibration of laboratory standard microphones type LS2P. The participating NMI's are HBK-DPLA (Denmark), CENAM (Mexico), GUM (Poland), INMETRO (Brazil), KRISS (Korea), LNE (France), METAS (Switzerland), NMIA (Australia), NMIJ (Japan), NMISA (South Africa), NRC (Canada), UME (Turkey) and VNIIFTRI (Russia). The role of Pilot laboratory was undertaken by LNE (France). The measurements took place between March 2019 and December 2020. Two LS2P microphones were circulated. This report includes the measurement results from the participants, information about their calibration methods, and the analysis leading to the assignment of the Key Comparison Reference Values (KCRV) and Degrees of Equivalence (DoE). To reach the ...
The study aimed to investigate the efficient pathway for BC sound transmission by measuring vibra... more The study aimed to investigate the efficient pathway for BC sound transmission by measuring vibrations on the opposite side of the skull bone, referred to as the mastoid position. The realistic contralateral transmission pathway of bone conduction (BC) vibrations is investigated through each osseous structure in the midlines of the fresh-frozen whole head. BC stimulation is applied to the mastoid using a bone vibrator, and acceleration responses are observed on the contralateral mastoid bone and seven midline points of skull bones using triaxial accelerometers. The study finds that the range showing the highest contralateral transmission efficiency of bone vibration is the intermediate frequency range with contralateral direction. Within this range, a significant amplitude of acceleration response is measured at the face-side points and the back and upper parts of the head. The thesis suggests that signal transmission from the specific midline to the mastoid can be more efficient th...
2008 International Conference on Control, Automation and Systems, 2008
To obtain the acoustic source condition from a given sound field data in an inverse manner is use... more To obtain the acoustic source condition from a given sound field data in an inverse manner is useful in achieving the target sound field in a detailed field distribution. A multi-unit acoustic source system comprises many loudspeakers to improve the performance and sometimes a modular array system can be used to realize a prescribed radiation pattern. To obtain an applicable solution for modular source system by inverse approach, relative magnitude and phase between sources in the same module are maintained at the same values. In this paper, a basic approach to practice the general inverse design method was studied. Two methods using the boundary element method and the equivalent source method were suggested. Validity of the suggested method was confirmed through a test example with the highly directional loudspeaker module.
The Journal of the Acoustical Society of America, 2013
Time-selective windowing techniques, which effectively remove multi-path noise, have been widely ... more Time-selective windowing techniques, which effectively remove multi-path noise, have been widely utilized for reciprocity calibration of microphone there are still limitations imposed by overlapping signals, particularly at low frequencies and for high Q microphones. Based on a fast Fourier transform analysis, the leakage due to a limited frequency range makes the overlap problem worse, not be perfectly separated. Instead of using conventional low-pass filters that are designed to have a flat response in the frequency range of interest, in this study, a filter with a Dolph-Chebyshev window shape was proposed because it has low sidelobe levels. After removing multi-path noise with a time-selective window, an inverse filter should be applied to compensate for distortion created by the applied filter. The method suggested in this paper extends the possible frequency range of free-field reciprocity calibration to frequencies below 2 kHz.
Main text The key comparison CCAUV.A-K6 has been carried out under the auspices of the Consultati... more Main text The key comparison CCAUV.A-K6 has been carried out under the auspices of the Consultative Committee on Acoustics, Ultrasound and Vibration (CCAUV) of the International Committee of Weights and Measures (CIPM). This comparison is concerned with primary pressure calibration of laboratory standard microphones type LS2P. The participating NMI's are HBK-DPLA (Denmark), CENAM (Mexico), GUM (Poland), INMETRO (Brazil), KRISS (Korea), LNE (France), METAS (Switzerland), NMIA (Australia), NMIJ (Japan), NMISA (South Africa), NRC (Canada), UME (Turkey) and VNIIFTRI (Russia). The role of Pilot laboratory was undertaken by LNE (France). The measurements took place between March 2019 and December 2020. Two LS2P microphones were circulated. This report includes the measurement results from the participants, information about their calibration methods, and the analysis leading to the assignment of the Key Comparison Reference Values (KCRV) and Degrees of Equivalence (DoE). To reach the ...
The study aimed to investigate the efficient pathway for BC sound transmission by measuring vibra... more The study aimed to investigate the efficient pathway for BC sound transmission by measuring vibrations on the opposite side of the skull bone, referred to as the mastoid position. The realistic contralateral transmission pathway of bone conduction (BC) vibrations is investigated through each osseous structure in the midlines of the fresh-frozen whole head. BC stimulation is applied to the mastoid using a bone vibrator, and acceleration responses are observed on the contralateral mastoid bone and seven midline points of skull bones using triaxial accelerometers. The study finds that the range showing the highest contralateral transmission efficiency of bone vibration is the intermediate frequency range with contralateral direction. Within this range, a significant amplitude of acceleration response is measured at the face-side points and the back and upper parts of the head. The thesis suggests that signal transmission from the specific midline to the mastoid can be more efficient th...
2008 International Conference on Control, Automation and Systems, 2008
To obtain the acoustic source condition from a given sound field data in an inverse manner is use... more To obtain the acoustic source condition from a given sound field data in an inverse manner is useful in achieving the target sound field in a detailed field distribution. A multi-unit acoustic source system comprises many loudspeakers to improve the performance and sometimes a modular array system can be used to realize a prescribed radiation pattern. To obtain an applicable solution for modular source system by inverse approach, relative magnitude and phase between sources in the same module are maintained at the same values. In this paper, a basic approach to practice the general inverse design method was studied. Two methods using the boundary element method and the equivalent source method were suggested. Validity of the suggested method was confirmed through a test example with the highly directional loudspeaker module.
The Journal of the Acoustical Society of America, 2013
Time-selective windowing techniques, which effectively remove multi-path noise, have been widely ... more Time-selective windowing techniques, which effectively remove multi-path noise, have been widely utilized for reciprocity calibration of microphone there are still limitations imposed by overlapping signals, particularly at low frequencies and for high Q microphones. Based on a fast Fourier transform analysis, the leakage due to a limited frequency range makes the overlap problem worse, not be perfectly separated. Instead of using conventional low-pass filters that are designed to have a flat response in the frequency range of interest, in this study, a filter with a Dolph-Chebyshev window shape was proposed because it has low sidelobe levels. After removing multi-path noise with a time-selective window, an inverse filter should be applied to compensate for distortion created by the applied filter. The method suggested in this paper extends the possible frequency range of free-field reciprocity calibration to frequencies below 2 kHz.
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