• Title/Summary/Keyword: Sound pressure Level

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Development of Obstacle Alarm for the Visually Impaired (시각 장애인을 위한 장애물 경보기의 개발)

  • 심현민;이응혁;민홍기;홍승홍
    • Proceedings of the IEEK Conference
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    • 2002.06e
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    • pp.113-116
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    • 2002
  • In this paper, we propose the sound-mapping algorithm of the detected obstacle by ultrasonic sensors. We apply this algorithm to a Obstacle alarm for the visually impaired. In our system, we acquire obstacles information using ultrasonic sensors, and transform two-dimensional and distance information into sound-imaging information and vibrator with azimuth (direction) and distance. We implement this system with ultrasonic sensors to more effective expression of the obstacle information. The distance of an obstacle can be expressed by sound pressure level, and azimuth of the obstacles can be expressed by inter-aural time difference (ITD) and inter-aural level difference (ILD) that are two important cues in a binaural system. These are the principal cues for sound localization, to detect sound source. In this system, the obstacle is substituted with a sound source. The visually impaired receive sound information of obstacles by headphone.

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A Study on the Evaluation of Sound Insulation Performance of Double Skin Facade -Focus on the Multi-story type of Double Skin Facade- (이중외피시스템의 차음성능 평가에 관한 연구 -전면형 이중외피시스템을 중심으로-)

  • 석호태;차민철
    • Journal of the Korean housing association
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    • v.15 no.2
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    • pp.11-18
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    • 2004
  • The purpose of this study is to evaluate the sound insulation performance and present fundamental data for sound insulation plan about open and close windows of inner facade and outer facade of Double-skin Facade system applied to multi-story type. The Headquarter of Green Building and the Energy Saving Building in the Korea Institute of Energy Research was selected for experiment. Measurement method which are specified in the Korea Standard 2235 were selected for this study. As the result of this study, 1) Sound insulation performance of Multi-layer type of Double-skin Facades is very excellent about outdoor noise. 2) Vertical level is higher, it shows that more decreases sound pressure level.

Experimental Study on the Cavitation Noise of a Hydrofoil (3차원 날개의 캐비테이션 소음 계측시험)

  • Lee, Seung-Jae;Seo, Jong-Soo;Han, Jae-Moon
    • Journal of the Society of Naval Architects of Korea
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    • v.44 no.2 s.152
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    • pp.111-118
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    • 2007
  • In order to investigate the noise characteristics of the different caviation, noise measurements were carried out in a large cavitation tunnel of the Samsuug Ship Model Basin(SSMB). The noise measurements for a 3-dimensional hydrofoil were carried out at the angle of attack of $12^{\circ}$ and $16^{\circ}$ according to the decrease in cavitation number. It is exhibited that sound pressure level(SPL) increased sharply with cavitation inception. The frequency of the noise induced by sheet cavitation was higher than that of tip vortex cavitation in the phase of cavitation inception. Within the range of the high frequency, in the case of fully developed cavitation, sheet cavitation noise was significantly increased in sound pressure level compared with tip vortex cavitation noise. In this study, the noise characteristics of the different cavitation types were considered experimentally and would be utilized as a basis for the analysis of propeller cavitation noise.

Estimation Method of Noise Reducing Devices Installed on the Noise Barrier(2) - Estimation by Sound Pressure Level - (방음벽 상단소음저감장치의 성능평가 방법에 관한 연구(2) - 음압레벨에 의한 평가 -)

  • Kim, Chul-Hwan;Chang, Tae-Sun;Lee, Ki-Jung;Kim, Dong-Joon;Jeong, Tae-Ryang;Chang, Seo-Il;Kim, Bong-Seok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.1125-1128
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    • 2007
  • In order to improve the acoustic performance of a noise barrier without increasing its height, various type of acoustic devices are suggested but, there is no proper method to estimate the performance in Korea. For this, an outdoor test facility was established in Expressway and Transportation Technology Institute(ETTI) of Korea Expressway Corporation for testing the acoustical performance of noise reducing devices installed on the top of a noise barrier. Noise measurements before and after installation of the noise reducing devices were carried out by using sound pressure level for long distance range from the barrier, from 10m to 40m. For considering the directivity effects of noise reducing devices, multivariate regression analysis was attempted.

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The Analysis of Eletroglottographic Measures of Vowel and Sentence in Korean Healthy Adults (한국 정상 성인의 모음과 문단 산출 시 전기성문파형 측정)

  • Kim, Jae-Ock
    • Phonetics and Speech Sciences
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    • v.2 no.4
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    • pp.223-228
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    • 2010
  • This study investigated the closed quotient and other voice quality parameters using electroglottography (EGG) in sustaining the vowel /a/ and reading a sentence at the comfortable pitch and loudness in healthy Korean adults. Seventy two healthy adults (36 men, 36 women) aged 20~40 years were included in the study. The tasks were recorded and analyzed using Lx Speech Studio. In vowel sustaining task, closed quotient (Qx), fundamental frequency (Fx), sound pressure level (SPL), Jitter, and Shimmer were measured. In sentence reading task, closed quotient (DQx), fundamental frequency (DFx), and sound pressure level (DAx) were measured. The sex effects were observed on Qx, Fx, Shimmer, DQx, and DFx. Men had significantly higher Qx and DQx than women, but had significantly lower Shimmer than women. However, there was no sex effect on Jitter. The task effects on Qx and SPL as well as DQx and DAx were also assessed. Qx and SPL were significantly higher than DQx and DAx in both gender. This study showed that the closed quotients in both vowel sustaining and sentence reading tasks were significantly related to other voice quality parameters. Therefore, clinicians and researchers should describe the voice quality parameters like fundamental frequency, sound pressure level, Jitter, Shimmer, and so on when reporting closed quotients using EGG.

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A Study on the ]Reduction of Flow induced Acoustic Noise for a High-speed Rotating Hexagonal Disk (고속회전 육각형 디스크의 유동기인 소음저감에 관한 연구)

  • Han Ji-Min;Rhim Yoon-Chul
    • 정보저장시스템학회:학술대회논문집
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    • 2005.10a
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    • pp.71-74
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    • 2005
  • The present study describes the prediction of the flow induced noise level of a high-speed rotating hexagonal disk and proposes the way how to reduce it. Since a hexagonal disk, which is used in the laser printer and named a Polygon mirror, has six sharp corners, there are low and high pressure regions on each of six edges when it rotates. Therefore, the pressure difference generates three dimension flow field and causes aerodynamic noise. The Ffowcs-Williams and Hawkings (FWH) method is employed for the analysis. We have measured the sound pressure levels and compared them with the computational results. The calculated sound pressure levels agree well with the experimental results. We modified the shape of the edges of a hexagonal disk to reduce the noise level and confirm their effects through numerical computation.

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Aerodynamic Analysis of Different Types of Singing Voices (가수 유형별 음성의 공기역학적 분석)

  • Noh, Dong-Woo;Hwang, Bo-Myung;Paik, Eun-A;Jeong, Ok-Ran
    • Speech Sciences
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    • v.8 no.4
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    • pp.131-138
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    • 2001
  • Sound pressure level, subglottic air pressure, vital capacity, adduction/abduction rate, and phonatory efficiency were measured in 19 opera singers, 17 Korean traditional 'Pansori' singers, and 20 non-singers; subjects' mean age was 25.9(SD=7.2) and the singers had been singing professionally for 5-10 years. One-way ANOVA and Scheff$\w'{e}$ post-hoc analysis were used to analyze aerodynamic data and to identify significant differences among groups. Sound pressure level, peak subglottic air pressure, and phonatory efficiency were found to be significantly different among three groups of the subjects. Differences in aerodynamic properties were discussed for their significance in diagnosis and treatment of voice disorders in professional singers.

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A Study on the Reduction of Flow Induced Acoustic Noise for a High-Speed Rotating Hexagonal Disk (고속회전 육각형 디스크의 유동기인 소음저감에 관한 연구)

  • Han, Ji-Min;Rhim, Yoon-Chul
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.168-171
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    • 2005
  • The present study describes the prediction of the flow induced noise level of a high-speed rotating hexagonal disk and proposes the way how to reduce it. Since a hexagonal disk, which is used in the laser printer and named a polygon mirror, has six sharp comers, there are low and high pressure regions on each of six edges when it rotates. Therefore, the Pressure difference generates three dimension flow field and causes aerodynamic noise. The Ffowcs-Williams and Hawkings(FWH) method is employed for the analysis. We have measured the sound pressure levels and compared them with the computational results. The calculated sound pressure levels agree well with the experimental results. We modified the shape of the edges of a hexagonal disk to reduce the noise level and confirm their effects through numerical computation.

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An Experimental Study on the Sound Level Intensity Characteristics for Combustion of Single Droplet Emulsified Fuels (유화단일액적의 연소에 관한 소음 특성 연구)

  • Cho, Seong-Cheol;Oh, Yang-Hwan;Im, Seok-Yeon
    • Journal of the Korean Applied Science and Technology
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    • v.31 no.3
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    • pp.492-499
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    • 2014
  • The objectives of this study was to examine experimentally the microexplosion phenomena of single droplet W/O(water-in-oil) type emulsified fuel. Also, measured the combustion characteristics of single droplet emulsified fuel for microexplosion phenomena in atmospheric pressure condition. The larger quantity of adding water makes microexplosion phenomenon with higher intensity of sound level, because larger water droplet has better coalescence for emulsified fuel. The small quantity of adding water makes puffing with lower sound level intensity. In latter period of extinction, large size droplet of the emulsified fuel breaks down rapidly to small size droplet, and microexplosion phenomenon occurs with multi step combustion.

Analysis of Sound Quality Parameters of Sound Sources applied for Soundscape Design (사운드 스케이프 적용 음원의 음질 지수 분석)

  • Park, Hyeon-Ku;Song, Min-Jeong;Jang, Gil-Soo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.814-819
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    • 2004
  • When we evaluate sound, there are various methods for noise such as A-weighted SPL(sound pressure level), NC(noise criteria), NR(noise rating) and SIL(speech interference level) etc. however, it is not sufficient for the sounds supplied to public places used in soundscape design. Consequently it is needed to develop the tool for evaluating the good acoustical environment and futhermore quantifying the effect of improvement by supplying sound sources. In this study, it was tried to analyse the sound sources applied for soundscape design using sound quality parameters. The sound sources used were natural sound artificial sound. For the sound quality parameters, Loudness(L), Sharpness(S), Fluctuation strength(FL), Tonality(T), Roughness(R), Unbiased Annoyance(UA) were used and sound quality values were compared both natural and artificial sounds, depending on the convolution of sound sources with background noise, the duration, the frequency contents and the SPL. As a result, the values of L and UA have shown to be changed comparing to the other parameters, and it is necessary to analyse the correlation with subjects' responses.

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