• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2000년도 춘계학술대회논문집
• /
• pp.1704-1709
• /
• 2000

This paper proposes a spherical probe allowing acoustic intensity measurements in three dimensions to be made, which creates a diffracted field that is well-defined, thanks to analytic solution of diffraction phenomena. Six microphones are distributed on the surface of the sphere along three rectangular axes. Its measurement technique is not based on finite difference approximation, as is the case for the ID probe but on the analytic solution of diffraction phenomena. In fact, the success of sound source identification depends on the inverse models used to estimate inverse diffraction phenomena, which has non-linear properties. In this paper, we introduce the concept of nonlinear inverse diffraction modeling using a neural network and the idea of 3 dimensional sound source identification with several tests.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2013년도 추계학술대회 논문집
• /
• pp.838-839
• /
• 2013

In this paper, optimum beamforming method using spherical microphone array is presented. Beamforming method has been recognized as an important study in localizing sound sources or visualizing acoustic fields in three-dimensional space. Its geometrical arrangement of sensors in space enables to process array signal to analyze the fields of interest by steering array response in three-dimensional.

• 한국콘텐츠학회지
• /
• 제14권4호
• /
• pp.39-42
• /
• 2016

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
• /
• pp.237-243
• /
• 2004

A multichannel smart sound sensor capable to detect and identify sound events in noisy conditions is presented in this paper. Sound information extraction is a complex task and the main difficulty consists is the extraction of high­level information from an one-dimensional signal. The input of smart sound sensor is composed of data collected by 5 microphones and its output data is sent through a network. For a real time working purpose, the sound analysis is divided in three steps: sound event detection for each sound channel, fusion between simultaneously events and sound identification. The event detection module find impulsive signals in the noise and extracts them from the signal flow. Our smart sensor must be capable to identify impulsive signals but also speech presence too, in a noisy environment. The classification module is launched in a parallel task on the channel chosen by data fusion process. It looks to identify the event sound between seven predefined sound classes and uses a Gaussian Mixture Model (GMM) method. Mel Frequency Cepstral Coefficients are used in combination with new ones like zero crossing rate, centroid and roll-off point. This smart sound sensor is a part of a medical telemonitoring project with the aim of detecting serious accidents.

• 한국음향학회지
• /
• 제13권3호
• /
• pp.41-50
• /
• 1994

이 연구에서는 3차원 음향 인텐시티를 동시에 측정할 수 있는 프로브를 이용하여 음향 인텐시티를 측정할 때 필연적으로 발생하는 오차를 컴퓨터의 수치계산으로 검토하였다. 이 3차원 음향 인텐시티 프로브는 Suzuki등에 의해 제안된 4개의 마이크로폰으로 구성된 것이고, 수치계산에서는 이상적인 점음원과 유한 크기를 가지는 면음원에 대해서 프로브의 각 축방향 및 임의의 방향에 대한 측정오차를 근거리 음장에서 분석하였다. 그 결과, 점음원의 경우 측정거리가 프로브를 구성하는 마이크로폰 사이의 간격보다 약 2.5배 이상 떨어진 거리에서 오차 1dB 이하의 정밀한 측정을 할 수 있었고, 유한 크기의 면음원의 경우, 면음원의 한 변의 길이가 0.02m이상일 때 근거리 음장의 측정오차가 크게 감소하기 시작하여, 한 변의 길이가 0.2m일 때 측정거리가 마이크로폰 사이의 간격보다 0.67배로 근접하여 측정하여도 1dB 이하의 정밀한 측정이 가능한 것으로 평가되어 이 프로브의 근거리 음장 측정의 유효성이 확인되었다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문집
• /
• pp.62-67
• /
• 2002

It has been shown that the vibrational response of a tire can be represented by a set of decaying waves, each associated with a particular cross-sectional mode shape in the region near the contact patch. Thus, it can be concluded that tires can be effectively modeled as lossy waveguides. It has also been shown that the sound radiation from tires is mainly from the region close to the contact patch. In consequence, it may be computationally efficient to analyze tire vibration and sound radiation in the region close to the contact patch by using a hybrid finite element model in which the cross-section of a tire is approximated by 2-D finite elements while an analytical wave solution is assumed in the circumferential direction of the tire. In this article. a hybrid finite element was formulated based on a composite shell model. The dispersion relations for sample structures obtained by using the hybrid FE model were then compared with those obtained by using a full, three-dimensional FE model. It has been shown that the FE analysis made using the hybrid 2-D finite elements yields results in close agreement with the three-dimensional model.

• 한국소음진동공학회논문집
• /
• 제27권2호
• /
• pp.139-147
• /
• 2017

Acoustic performance of splitter silencers was investigated by using 3-dimensional commercial software and experiments. Flow resistivity of sound absorbing material was indirectly estimated by using an impedance tube setup and a curve fitting method. In addition the acoustic impedance of perforated plate was determined by an empirical formulation. Such properties have been used as input parameters in the commercial software. The prediction for a splitter silencer with 1000 mm length was compared with the experimental result. The numerical method is then applied to identify the effects of number of splitters, length of splitters, absorptive material density, and porosity of a perforated plate on the performance of the splitter silencers. As the number and length of splitter increases, the acoustic performance significantly increases. Although the increase of density of absorptive material also increase the acoustic performance, a change in the density over a certain level hardly affect it. The increase of porosity will enhance the performance especially at higher frequencies.

• 한국소음진동공학회논문집
• /
• 제24권4호
• /
• pp.282-288
• /
• 2014

Three-dimensional multimedia industry such as 3D TV, movie and broadcast has been developed vividly. For generating 3D contents with high quality, virtual auditory display, so called VAD, is being researched to offer more realistic experience to listeners. When people render VAD using headphones or two speakers, head-related transfer function(HRTF) plays a key role. The best solution is measuring all individuals' HRTFs, but it is hard to measure all listeners' HRTFs. To overcome this difficulty, many research groups have tried to construct their own measurement system and to build HRTF databases. However, some of them have not enough subjects or spatial resolution and they are mainly focused on Caucasian. There exists difference between Korean and Caucasian in a view of physical features. In other words, if Koreans hear three-dimensional sound rendered by HRTF database based on Caucasian, performance might be hindered. To verify this possibility and remedy the drawbacks, construction of new HRTF database aimed at Korean is needed. Therefore, our laboratory built HRTF measurement system which can measure HRTF of three-dimensional space with dense spatial resolution. With this system, 55 Korean males and 45 females' HRTFs were measured and Korean HRTF database was built based on these data.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2004년도 춘계학술대회 논문집
• /
• pp.61-67
• /
• 2004

이 연구에서는, 인간(해기사)의 두 귀에 주목한 머리전달함수(HRTF)를 이용하여, 기적음과 관련된 해양사고를 분석-평가하기 위한 시뮬레이션 시스템(3D-LSS)을 개발하였다. 해양사고당시 상황을 분석해서 가청화 모델을 구축하고, 3차원음 생성방법과 평가방법을 제시하였다. 개발한 시스템은 CUI 방식의 그래픽과 3차원 음향으로 해양사고 당시의 상황을 묘사하고, 시뮬레이션할 수 있도록 구성하였다. 3D-LSS을 이용하여, 해양사고 중에서 기적음 청취여부를 판단하지 못했던 6가지 사건을 대상으로 실험하였다. 5명의 평가자에 의한 심리음향평가결과, 6가지 사건을 시각적 청각적으로 명확하게 평가할 수 있었기 때문에 3D-LSS의 해양사고 심판보조 장치로서의 활용가능성을 확인할 수 있었다.

• 한국전산유체공학회지
• /
• 제17권4호
• /
• pp.103-109
• /
• 2012

Sound scattering in 3D complex geometry is difficult to model with body-fitted grid. Thus Brinkman Penalization method is used to compute sound scattering in 3D complex geometry. Sound propagation of monitor/TV is studied. The sound field for monitor/TV is simulated by applying Brinkman Penalization method to Linearized Euler Equation. Solid Structure and ambient air are represented as penalty terms in Linearized Euler Equation.