• Title, Summary, Keyword: Sound characteristics

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Acoustic Properties of Solid Materials: Sound Speed, Transmission Coefficient, and Attenuation

  • Roh Heui-Seol;Lee Kang Il;Jung Kyung-Il;Yoon Suk Wang
    • Proceedings of the Acoustical Society of Korea Conference
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    • pp.525-528
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    • 2002
  • The speed of sound, transmission coefficient, and attenuation are measured around the center frequency 1 and 2 MHz in solid materials such as bone, sediment, rubber, and Lucite materials. Common and different characteristics of such materials in the sound speed, transmission coefficient, and attenuation are discussed. Ambiguities in estimating such acoustic characteristics we also addressed. Ultrasonic properties of the first and second kind waves are clarified for different materials. Discussions are concentrated on classes of sound speed, broadband ultrasonic attenuation (BUA), and correlations of sound speed and BUA with apparent density. New correlations of inverse sound speed square and BUA with apparent density are suggested.

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A Study on the Floor-Specific Characteristics of Road Traffic Noise in Apartment Buildings (공동주택의 층별 도로교통 소음의 전달 특성에 관한 연구)

  • Ham, Jin-Sik
    • Journal of the Korean housing association
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    • v.19 no.1
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    • pp.1-8
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    • 2008
  • This study is an attempt to understand the floor-specific characteristics of facade road traffic noise in apartment buildings. For this purpose, it sampled a total of seven roadside apartment building complexes: three with no soundproof bar barrier installed at roadside, one with a forest buffer zone, one with a sound-absorbing hill, and two with soundproof barriers. The measured noise level was highest on the 5th floor of apartment buildings with no soundproof barrier, and the upper stories from the 5th floor showed lower-noise measurements in order. For apartment buildings with soundproof barriers, however, the noise level was lower on the 10th floor than the 5th floor. Two apartment building groups--one with a sound-absorbing hill and the other with no soundproof barrier--showed similar measurement results in the floor-specific characteristics of facade road traffic noise. This suggests that such installations have little sound insulation effect. In the apartment building complex with a forest buffer zone around it, a slight sound insulation effect was measured on the lower floors of the buildings.

Analysis of Acoustic Psychology of City Traffic and Nature Sounds (도심 교통음과 자연의 소리에 대한 음향심리 분석)

  • Kyon, Doo-Heon;Bae, Myung-Jin
    • The Journal of the Acoustical Society of Korea
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    • v.28 no.4
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    • pp.356-362
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    • 2009
  • In modern society, most people of the world are densely populated in cities so that the traffic sound has a very significant meaning. people tend to classify traffic sound as a noise pollution while they are likely to categorize most nature sound as positive. In this paper, we applied various forms of FFT filters into white noise belonged in nature sound to find frequency characteristics of white noise which preferred by people and confirm its correlation with nature sound. In addition, we conducted an analysis through the comparison of various traffic and nature sound waveforms and spectra. As a result of analysis, the traffic sound have characteristics which sound energy had concentrated on specific frequency bandwidth and point of time compared to nature sound. And we confirmed the fact that these characteristics had negative elements to which could affect to people. Lastly, by letting the subjects listen directly to both traffic and nature sound through brainwave experiment using electrode, the study measured the energy distribution of alpha waves and beta waves. As a result of experiments, it has been noted that urban sound created a noticeably larger amount of beta waves than nature sound; on the contrary, nature sound generated positive alpha waves. These results could directly confirm the negative effects of traffic sound and the positive effects of nature sound.

Transient Rumbling Index Development of Sound Quality on a Passenger Car (승용차 과도음에 대한 럼블링 음질 인덱스 개발)

  • 김병수;이상권;박동철;정승균
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.377-382
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    • 2003
  • In our previous study, we have developed sound quality index for steady rumbling sound of passenger car. In this paper, we will study sound quality index for transient rumbling noise. The subjective evaluation of rumbling sound can be indicated to objective parameters by sound metrics of psychoacoustics and principal rumble component. And artificial neural network can be estimated complexity and nonlinear characteristics of relation between subjective evaluation and sound metrics. We applied to sound metrics and artificial neural network to development of sound quality index for transient rumbling sound of passenger car.

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The Study on Cognition Difference of Environmental Sounds due to Subject' Classes (환경음에 대한 계층별 인식 차이에 관한 조사 연구)

  • Shin, Hoon;Baek, Geon-Jong;Song, Min-Jeong;Jang, Gil-Soo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1187-1190
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    • 2007
  • This study aims to induce acoustic environmental characteristics which could be used for soundscape design by carrying out factor analysis on sound source image and cognition analysis on subjects' responses on selective questions due to class differences. The results of this study are as follows ; Satisfaction rate differences on exterior acoustic environment due to sensitivity and residence year were revealed. After factor analysis of living sound sources' image, it is known that natural sound, traditional sound, socials traffic sound, rural sound, religious sound and the others are main factors. Social traffic sound is the most one that should be eliminated and traditional sound is selected as a most Korean-like sound. Natural sound is evaluated as the most one that should be preserved and the most retrospectively one.

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Booming Index Development of Interior Sound Quality on a Passenger Car Using Artificial Neural Network (신경망회로를 이용한 부밍음질의 인덱스 개발에 관한 연구)

  • 이상권;채희창;박동철;정승균
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.6
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    • pp.445-451
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    • 2003
  • Booming sound is one of the most important interior sound of a passenger car. The conventional booming noise research was focused on the reduction of the A-weighted sound pressure level. However A-weighted sound pressure level cannot give the whole story about the booming sound of a passenger car. In this paper, we employed sound metrics, which are the subjective parameters, used in psycoacoustics. According to recent research results. the relation between sound metrics and subjective evaluation is very complex and has nonlinear characteristics. In order to estimate this nonlinear relationship, artificial neural network theory has been applied to derivation of sound quality index for booming sound of a passenger car.

New Development of Two-dimensional Sound Quality Index for Brand Sound in Passenger Cars (승용차 브랜드 사운드를 위한 이차원 음질 인덱스 개발)

  • Jo, Byoung-Ok;Park, Dong-Chul;Lee, Min-Sub;Jung, Seung-Gyoon;Lee, Sang-Kwon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.5
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    • pp.457-469
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    • 2006
  • In automotive engineering, the brand sound is one of the important advantage strategies in a car company. For the design of brand sound, the selection of descriptive word for a car sound is one of major works in automotive sound quality research. In this paper, booming and rumbling sound, which are professional words used by sound and vibration engineers are used for the design of brand sound. We employed sound quality metrics, which are used in the psychoacoustics. By most research results, the relationship between subjective evaluations and sound quality metrics has nonlinear characteristics. In order to correlate these subjective evaluations with sound quality metrics, the artificial neural network technology has been applied to two-dimensional sound quality index for a passenger car. These indexes are used for 46 passenger cars, which are samples of the famous cars around the world. Also a preference evaluation for car sound was carried out by sound and vibration engineers. We coupled this preference with booming and rumbling sounds by using artificial neural network. In future, the two dimensional sound and preference index will be very useful to develop brand sound in passenger cars.

A Study on the Cataloging of Sound Recordings (녹음자료의 목록에 관한 연구)

    • Journal of Korean Library and Information Science Society
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    • v.32 no.1
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    • pp.125-150
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    • 2001
  • The purpose of this study is to investigate the distinctiveness and problem areas in cataloging rules of sound recordings. In this study, therefore, the characteristics and kinds of sound recordings and the cataloging rules related to sound recordings in non-book cataloging rules are examined first as the backgrounds. Then the sources of information, general material designation, physical description, choice of headings, and uniform titles in ISBD(NBM)·AACR2R·AECT4 and KORMARC(NBM) are analyzed. And the special issues and some problems to be considered in cataloging of sound recordings are presented.

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Externalization of sound image in 3D sound system based on headphone

  • Youngsik Yoon;Park, Youngjin
    • 제어로봇시스템학회:학술대회논문집
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    • pp.51.3-51
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    • 2002
  • 3D sound user often finds the results that the sound image appear to originate either inside, or close to, the head when he uses headphone-based binaural system. This phenomenon is called in-head localization(IHL). The main factors were chosen to evaluate externalization performance : individualized HRTFs, near-field HRTF characteristics and reverberation. Direct comparison was conducted among them, especially two factors\ulcorner reverberation and near-field HRTFs.

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Multidisciplinary Design Optimization for Acoustic Characteristics of a Speaker Diaphragm (스피커 진동판의 음향특성 다분야통합최적설계)

  • Kim, Sung-Kuk;Lee, Tae-Hee;Lee, Surk-Soon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.763-766
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    • 2004
  • Recently, various acoustic artifacts that contains speaker have been produced such as cellular phone. Speaker consists of diaphragm generating sound and coil vibrating diaphragm. Generally, good speaker means that it has a wide frequency range, high output power rate to input power and flat sound pressure level in specified frequency range. Acoustic characteristic was estimated through the experiment and computer simulation, or sound power was controlled with acoustic sensitivity in a natural frequency range fer last decade. However, the flatness of sound pressure level has not been considered to enhance the sound quality of a speaker. Tn this study, a method for speaker design is proposed for a good acoustic characteristic, which is flatness of SPL(sound pressure level) and wideness between the first and second natural frequency. SYSNOISE is used fer acoustic analysis and ANSYS is used for harmonic response analysis and modal analysis. Optimization for acoustic characteristics of a speaker diaphragm is performed using ModelCenter. All analyses are done within a frequency domain. And we confirm that the experimental and computational simulations have similar trend.

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