• Title/Summary/Keyword: Vibration sound of glass window

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Speech Intelligibility Analysis on the Vibration Sound of the Glass Window of a Conference Room (회의실 유리창 진동음의 음성 명료도 분석)

  • Kim, Hee-Dong;Kim, Yoon-Ho;Kim, Seock-Hyun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.4 s.121
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    • pp.363-369
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    • 2007
  • The purpose of the study is to obtain acoustical information to prevent eavesdropping of the glass window. Speech intelligibility was investigated on the vibration sound detected from the glass window of a conference room. Objective test using speech transmission index(STI) was performed to estimate quantitatively the speech intelligibility. STI was determined based on tile modulation transfer function(MTF) of the room-glass window system. Using Maximum Length Sequency(MLS) signal as a sound source, impulse responses of the glass window and MTF were determined by signals from accelerometers and laser doppler vibrometer. Finally, speech intelligibility of the interior sound and window vibration were compared under different sound pressure levels and amplifier gains to confirm the effect of measurement condition on the speech intelligibility.

Speech Intelligibility Analysis on the Vibration Sound of the Window Glass of a Conference Room (회의실 유리창 진동음의 명료도 분석)

  • Kim, Yoon-Ho;Kim, Hee-Dong;Kim, Seock-Hyun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.150-155
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    • 2006
  • Speech intelligibility is investigated on a conference room-window glass coupled system. Using MLS(Maximum Length Sequency) signal as a sound source, acceleration and velocity responses of the window glass are measured by accelerometer and laser doppler vibrometer. MTF(Modulation Transfer Function) is used to identify the speech transmission characteristics of the room and window system. STI(Speech Transmission Index) is calculated by using MTF and speech intelligibility of the room and the window glass is estimated. Speech intelligibilities by the acceleration signal and the velocity signal are compared and the possibility of the wiretapping is investigated. Finally, intelligibility of the conversation sound is examined by the subjective test.

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A Study on the Eavesdropping of the Glass Window Vibration in a Conference Room (회의실내 유리창 진동의 도청에 대한 연구)

  • Kim, Seock-Hyun;Kim, Yoon-Ho;Heo, Wook
    • Journal of Industrial Technology
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    • v.27 no.A
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    • pp.55-60
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    • 2007
  • Possibility of the eavesdropping is investigated on a conference room-glass window coupled system. Speech intelligibility analysis is performed on the eavesdropping sound of the glass window. Using MLS(Maximum Length Sequency) signal as a sound source, acceleration and velocity responses of the glass window are measured by accelerometer and laser doppler vibrometer. MTF(Modulation Transfer Function) is used to identify the speech transmission characteristics of the room and window system. STI(Speech Transmission Index) is calculated by using MTF and speech intelligibility of the vibration sound is estimated. Speech intelligibilities by the acceleration signal and the velocity signal are compared.

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The Effect of the Disturbing Wave on the Speech Intelligibility of the Eavesdropping Sound of a Window Glass (교란파가 유리창 진동음의 음성명료도에 미치는 영향)

  • Kim, Seock-Hyun;Kim, Hee-Dong;Heo, Wook
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.9
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    • pp.888-894
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    • 2007
  • The speech sound is detected by the vibration measurement of the window glass. In this study, we investigate the effect of the disturbing waves by background noise and window shaker excitation on the speech intelligibility of the detected sound. Based upon Modulation Transfer Function(MTF), speech intelligibility of the sound is objectively estimated by Speech Transmission Index(STI) As the level of the disturbing wave varies, variation of the speech intelligibility is examined. Experimental result reveals how STI is influenced by the level and frequency characteristics of the disturbing wave. By using a customized window shaker for disturbing sound, we evaluate the efficiency and the frequency characteristics of the anti-eavesdropping system. The purpose of the study is to provide useful information to prevent the eavesdropping through the window glass.

Performance Estimation of a Window Shaker (유리창 도청방지 장치의 성능평가)

  • Kim, Seock-Hyun;Kim, Hee-Dong;Heo, Wook
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.649-654
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    • 2007
  • Eavesdropping prevention performance is evaluated on a commercial window shaker, which is used to prevent a glass window from eavesdropping. Speech transmission index (STI) is introduced in order to estimate quantitatively the speech intelligibility of the sound detected on the glass window. Objective test by IEC standard using modulation transfer function (MTF) is performed to determine STI. Using Maximum Length Sequency (MLS) signal as a sound source, MTF is measured by accelerometers and laser doppler vibrometer. STI under different level of disturbing wave are compared to confirm the disturbing effect on the speech intelligibility.

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Eavesdropping of the Glass Window Using a Laser Sensor and Performance Estimation of a Window Shaker (레이저센서를 이용한 유리창 도청 및 도청방지기의 성능 평가)

  • Kim, Seock-Hyun;Heo, Wook;Kim, Hee-Dong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.551-556
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    • 2008
  • Possibility of the remote eavesdropping through window glass is investigated using a laser sensor. Various thicknesses and types of glass windows are excited by maximum length sequency (MLS) signal and the vibration sound is detected by a laser doppler vibrometer. Intelligibility of the detected sound is evaluated using the speech transmission index (STI), which is based on the modulation transfer function (MTF). In order to identify the disturbing effect, different level of disturbing wave is generated by an outside speaker and a window shaker attached on the glass window. On the different thickness of glass windows, decrease effect of the speech intelligibility is analysed.

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Intelligibility Analysis on the Eavesdropping Sound of Glass Windows Using MTF-STI (MTF-STI를 이용한 유리창 도청음의 명료도 분석)

  • Kim, Hee-Dong;Kim, Yoon-Ho;Kim, Seock-Hyun
    • The Journal of the Acoustical Society of Korea
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    • v.26 no.1
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    • pp.8-15
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    • 2007
  • Speech intelligibility of the eavesdropping sound is investigated on a acoustic cavity - glass window coupled system. Using MLS (Maximum Length Sequency) signal as a sound source, acceleration and velocity responses of the glass window are measured by accelerometer and laser doppler vibrometer. MTF (Modulation Transfer Function) is used to identify tile speech transmission characteristics of the cavity and window system. STI (Speech Transmission Index) based upon MTF is calculated and speech intelligibility of the vibration sound of the glass window is estimated. Speech intelligibilities by the acceleration signal and the velocity signal are compared. Finally, intelligibility of the conversation sound is confirmed by the subjective test.

The Development and Application of Sound Quality Index for the Improving Sound Quality to Road Vehicle Power Window System (차량 윈도우 리프트 음질 향상을 위한 음질 지수 제작 및 개선에의 응용)

  • Kim, Seong-Hyeon;Park, Dong-Chul;Jo, Hyeon-Ho;Seong, Won-Chan;Kang, Yeon-June
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.10a
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    • pp.525-530
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    • 2013
  • With the increasing the importance of emotional quality of vehicle, the sound quality of systems with electric motor components has become increasingly important. Electric motors are used for windows, seats, sun roof, mirrors, steering columns, windshield wiper, climate control blowers, etc. In this paper, a study was conducted to identify sound quality factors that contribute to customer's satisfaction and preference of the window lift system. Jury test for subjective evaluation was carried out and sound quality index was developed. Averaged sound pressure level and sharpness were significant factors when glass moves down. Also, maximum loudness at stop section and averaged loudness were significant factor when glass moves up. Noise source identification was carried out for the reduced the loudness and sharpness during glass transferred section and impulsive noise at stop section, Using the source identification result, several improvement points were applied. And finally, the degree of sound quality improvement was judged using sound quality index.

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The Development and Application of Sound Quality Index for the Improving Luxury Sound Quality of Road Vehicle Power Window System (차량 윈도우 리프트 음질 고급감 향상을 위한 음질 지수 제작 및 개선에의 응용)

  • Kim, Seonghyeon;Park, Dong Chul;Jo, Hyeonho;Sung, Weonchan;Kang, Yeon June
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.2
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    • pp.108-116
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    • 2014
  • With the increasing the importance of emotional quality of vehicle, the sound quality of systems with electric motor components has become increasingly important. Electric motors are used for windows, seats, sun roof, mirrors, steering columns, windshield wiper and climate control blowers, etc. In this paper, a study was conducted to identify sound quality factors that contribute to customer's satisfaction and preference of the window lift system. Jury test for subjective evaluation was carried out and sound quality index was developed. Averaged sound pressure level and sharpness were significant factors when glass moves down. Also, maximum loudness at stop section and averaged loudness were significant factor when glass moves up. Next, noise source identification was carried out using beam forming method during glass transferred section and impulsive noise at stop section. Several improvement methods were applied using the source identification result. And finally, the degree of sound quality improvement was judged using sound quality index.

Speech Intelligibility Analysis on the Laser Detected Sound of the Glass Windows (유리창의 레이저 탐지음에 대한 음성명료도 분석)

  • Kim, Seock-Hyun;Lee, Hyun-Woo;Kim, Hee-Dong
    • The Journal of the Acoustical Society of Korea
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    • v.28 no.2
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    • pp.127-134
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    • 2009
  • In this study, possibility of the laser eavesdropping is investigated on the window glasses with various thicknesses, Glass windows are excited by maximum length sequency (MLS) signal and the vibration sound is detected by a laser doppler vibrometer. From the detected sound, speech intelligibility is objectively estimated. Speech transmission index (STI), which is based on the modulation transfer function (MTF). is calculated for the estimation. Finally, disturbing wave effect on the speech intelligibility is analysed by using an outside speaker and a window shaker attached on the glass window. The purpose of the study is to estimate the possibility of remote eavesdropping by the laser sensor and to evaluate the performance of the homemade window shaker to protect from the remote eavesdropping.