• 말소리와 음성과학
• /
• 제5권4호
• /
• pp.227-232
• /
• 2013

Since a reverberation filter is generally much shorter than the corresponding dereverberation filter, a single-channel speech dereverberation method based on reverberation filter estimation has been developed to improve its performance. Unfortunately, a typical reverberation filter still requires too many coefficients to be accurately estimated using limited speech observations. In order to exploit sparseness of reverberation filter coefficients, in this paper, we present an algorithm to impose a sparse prior to the process of reverberation filter estimation. Simulation results demonstrate that the sparse prior imposition further improves performance of the speech dereverberation method based on reverberation filter estimation.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2011년도 추계학술대회 논문집
• /
• pp.92-95
• /
• 2011

The walls of modern train cars are required to have higher transmission loss since modern train have had high speed and light weight. The method based on Reverberation Chamber like KS F 2808 could be used to measure transmission loss. However, this method has difficulty in that constrained Standard of it requires extremely large facilities. Recently, the method based on Scale Reverberation Chamber is used as an alternative to Reverberation Chamber. The method of Scale Reverberation Chamber is known to be small and economical but it provides standing wave that directly influences measurement error. Therefore, this research is focus on predicting standing waves based on method of FFM and reducing measurement error by changing shape of chamber.

• 한국음향학회지
• /
• 제28권8호
• /
• pp.755-760
• /
• 2009

본 논문에서는 근거리에 위치한 수중 장애물의 탐지 성능을 향상시키기 위해 잔향의 영향을 감소시키는 여러 기법 중 특이 값 차이를 이용한 잔향 감소 기법을 적용한다. 특이 값 차이를 이용한 잔향 감소 기법은 중심 빔 신호에 잔향과 표적이 포함되어 있다고 가정하고 인접한 빔 신호를 참조 신호로 사용하여 중심 빔 신호와의 특이 값 차이를 이용함으로써 잔향 신호를 감소시킨다. 그리고 한국 근해에서 십자형 구조의 송수신 장치를 통해 얻어진 실측 데이터를 이용하여 수중 장애물 탐지에서의 제시한 기법의 타당성을 검증한다.

• 한국음향학회지
• /
• 제37권5호
• /
• pp.349-355
• /
• 2018

실내의 음향 특성을 기술하고 평가하기 위한 많은 파라미터들이 있다. 잔향 시간은 콘서트 홀, 극장, 스튜디오 등에서 중요한 특성이다. 오랫동안 잔향 시간을 계측하는 많은 방법들이 개발되어 왔고, 가장 일반적인 것은 단속적인 잡음 방법, 임펄스 응답 적분 방식, 임펄스성 음원에 대한 실내 응답 녹음 방법들이 있다. 그러나 잔향 시간은 측정 방법과 사용하는 음원과 마이크로폰에 따라서 달라지므로 정확한 잔향 시간을 구하기 어렵다. 본 논문에서는 잔향 시간의 해석 방법을 분석하고, 한계점에 대해서 검토한다.

• Journal of Mechanical Science and Technology
• /
• 제17권4호
• /
• pp.511-520
• /
• 2003

In room acoustics, reverberation time is an important acoustic parameter. However it is often difficult to measure short reverberation times at low frequencies with a traditional band pass filter bank if the product of filter bandwidth (B) and reverberation time (T) is small. It it well known that the minimum permissible product of bandwidth and reverberation time of the traditional band pass filter is at least 16. This strict requirement makes it difficult to measure short reverberation times of an acoustic room at low frequencies exactly. In order to reduce this strict requirement, in the previous paper, the wavelet filter bank was developed and the minimum permissible product of bandwidth and reverberation time was replaced with 4. In the present paper it is demonstrated how the short reverberation times of an practical room at low frequencies are successfully measured by using the wavelet filter bank and the results are compared with the traditional method using a band past filer bank.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 1996년도 춘계학술대회논문집; 부산수산대학교, 10 May 1996
• /
• pp.275-285
• /
• 1996

A noise measurement method of the multi-sound sources in a reverberation field with wave-guide is developed by experimental method. In the reverberation field, it is very hard to measure sound level or noise spectra of a certain sound source, when many sound sources generate noise simultaneously with a small space between them. Flexible wave-guide(tube) was used to measure noise level in a reverberation field. One end of the tube is attached to a sound source and the other end is closed with an anechoic terminal. Detailed method of the measurement and the source of error was considered as well.

• 한국해양공학회지
• /
• 제33권4호
• /
• pp.358-363
• /
• 2019

The acoustic power is used as a primary index characterizing underwater sound sources and could be defined by its source level. The source level has been assessed using various experimental techniques such as the reverberation time method and reverberant tank plot method. While the reverberation time method requires reverberation time data extracted in a preliminary experiment in a reverberant water tank, the reverberant tank plot method only needs acoustic pressure data directly obtained at the reverberation water tank. In this research, these experimental techniques were studied in comparative experiments to estimate the source levels of underwater sources in a reverberant water tank. This paper summarizes the basic theories and procedures of these experimental techniques and presents the experimental results for an underwater source in a long cuboid water tank using each technique, along with a discussion.

• 한국음향학회지
• /
• 제21권5호
• /
• pp.494-502
• /
• 2002

본 연구는 실측 잔향음 자료에서 나타나는 단주기적 시변동성 신호 간섭 (interference)을 억제하기 위해 Ecart-Young 이론을 토대로 자료 행렬로부터 낮은 계수를 추출하여 근사화하는 낮은 계수 근사법 (LRA: Low Rank Approximation) 기법을 제안하였다. 이 기법을 실측 자료에 적용한 결과, 잔향음 신호와 시변동성 신호가 분리되었으며 이때 적절한 낮은 계수를 추출키 위해서 특이치 분해법 (SVD: Singular Value Decomposition)이 사용되었다. 잔향음 신호의 억제는 LRA를 통해 얻어진 근사치와 실측치 사이의 잔차를 계산함으로써 수행하였으며 결과적으로 LRA을 이용하여 시간적으로 안정적인 잔향음 신호를 획득함으로써 능동 소오나 시스템 운용 및 잔향음 모델링시 적용 가능성을 제시하였다.

• 한국소음진동공학회논문집
• /
• 제25권4호
• /
• pp.291-298
• /
• 2015

In this study, the reverberation time of apartment living room was measured and distribution of the reverberation time was analyzed. In addition, sound field characteristics of mock-up test room similar with living room and timber structured bedroom was investigated with addition of furniture and sound absorption material. Average reverberation time of unfurnished apartment unit was 1.11 s, and reverberation time in 630 Hz~2000 Hz bands were longer than 1.2 s. It was found that from the field measurement results, reverberation time characteristic of furnished apartment living room was uniform in most of frequency bands. Averaged reverberation time of furnished living room was 0.48 s and the reverberation time of bedroom was 0.44 s. Standardized sound pressure level correction values were calculated from the average reverberation time of furnished and unfurnished apartment units. The correction value of unfurnished living room was −3.4 dB and that of furnished living room was 0.2 dB. Measured reverberation time of furnished and unfurnished apartment units indicated that reference reverberation time; 0.5 s, in KS and ISO standards is reasonable also in Korean residential environment.

• 한국음향학회지
• /
• 제25권6호
• /
• pp.257-268
• /
• 2006

도자기 컵의 결함여부를 판정하는 간편한 방법으로 실내에서 충격 시험으로 추정한 유사잔향시간을 사용하는 방법을 제시하였다. 정상적인 도자기 컵과 미세한 균열이 있는 컵에 대하여 충격 시험을 하여 발생하는 충격음에서 구한 슈레더 곡선에서 잔향 시간을 추정하였다. 충격 가진 막대의 종류와 가진 위치, 경계 조건에 따라 잔향 시간을 추정하였고 추정된 잔향 시간으로부터 도자기 컵의 결함 유무를 효과적으로 파악할 수 있는지를 기술하였다