• Journal of Industrial Technology
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• 제41권1호
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• pp.15-20
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• 2021

This work proposes a simple method to use the added absorption per person values to predict the expected values of the acoustical conditions in occupied classrooms. This method is based on the effects of the values of added absorption per person on the unoccupied total absorption values of the classrooms and on other room acoustical parameters. The total sound absorption in an unoccupied classroom can be calculated from measured reverberation times in the classroom. The expected occupied absorption can be calculated using equation which was obtained in a previous study (Choi, 2017) by fitting a linear regression line to a plot of total occupied absorption versus the corresponding unoccupied total absorption values measured in 12 university classrooms. The ratios of occupied-to-unoccupied sound absorption are used to predict increments in the values of acoustical parameters that result when occupants are added to the rooms.

• The Journal of the Acoustical Society of Korea
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• 제37권5호
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• pp.343-348
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• 2018

This paper proposes a simple procedure for estimating the acoustical parameter values in an occupied classroom from measurements in the unoccupied classroom. The total sound absorption in an unoccupied classroom can be calculated from measured reverberation times in the room. The expected occupied absorption can be calculated using equation that was obtained in a previous study (Choi, 2016) by fitting a linear regression line to a plot of total occupied absorption versus the corresponding unoccupied total absorption values measured in 12 university classrooms. The ratios of occupied-to-unoccupied sound absorption are used to predict increments in the values of acoustical parameters when occupants are added to the rooms. Occupied values of acoustical parameters can be estimated from unoccupied values and the change in total room absorption due to adding occupants.

• The Journal of the Acoustical Society of Korea
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• 제18권5호
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• pp.63-67
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• 1999

Recently, a method of measuring impulse response is widely used for a room acoustic evaluation instead of measuring reverberation time by white noise excitation. Comparing with the traditional reverberation time measurement, this method has many advantages such as good repeatability and the ability to extract various room acoustic parameters at one measurement. In this study, the author developed a measuring system that can extract mono-aural room acoustic parameters from an impulse response measured with MLS (Maximum Length Sequence) signal excitation. These room acoustic parameters include reverberation times(EDT, RT), speech intelligibilities(C50, C80, D, U50, U80, AI) and sound strength(G). This paper introduces the configuration of the developed measuring system, test results and discussions for the measurements at several rooms.

• The Journal of the Acoustical Society of Korea
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• 제38권2호
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• pp.139-144
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• 2019

Various room acoustic parameters and their optimal values were proposed and verified as proper interpretations to the listeners' preference of concert hall sounds. However the listening environment has been changed since they were developed, and the listeners' preference may not be the same among countries of different cultural backgrounds. Actual listeners' preference should be applied to the design of a new concert hall. A survey on the listening preference was carried out for 22 music experts. A room acoustical design process was proposed which made the acoustical environment of a concert hall as close to the listeners' preferences.

• The Journal of the Acoustical Society of Korea
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• 제19권1호
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• pp.48-53
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• 2000

To analyze a room reverberation, many objective parameters have been suggested as measures of subjective perception in concert hall acoustics. However, it is difficult to understand the relationship among the individual parameters and to have a whole image of them. In this paper five primary objective parameters were selected and a reverberation model based on them was established by the reverberation decay curve. The proposed model was interpreted geometrically in terms of subjective characteristics. And finally we discuss the usefulness and the limitation of the model when it is applied to the analysis and.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.443-448
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• 2005

This study aimed to evaluate the room acoustical performances of multi-purpose halls, analyzing the architectural features by survey and the acoustical characteristics by measurements. Moreover, vocabularies appropriate for the evaluation of the room acoustical performance were determined through questionnaire and subjective responses. From the correlation analysis and factor analysis to the physical values through measurements and the subjective evaluation using vocabularies, useful vocabularies for the evaluation of multi-purpose halls' acoustical performances were determined and physical parameters corresponding to the vocabulary were identified.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.392-396
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• 2001

Revision of KS, Korean Standards, is currently actively discussed. It is just the time for a new world class standards under the new system with WTO, World Trade Organization. This paper is a part of “Researchs on the Standards in the Building Acoustic Field”, as one of KS revision projects. The aim of this study is to define the requirements for measuring the reverberation time and other major room acoustical parameters.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.230-233
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• 2001

Revision of KS, Korean Standards, is currently actively discussed. It is just the time for a new world class standards under the new system with WTO, World Trade Organization. This paper is a part of "Researches on the Standards in the Building Acoustic Field", as one of KS revision projects. The aim of this study is to define the requirements for measuring the reverberation time of rooms with reference to other acoustical parameters. In the former KS, there is no items matched with this purpose. Therefore measuring reverberation time and other room acoustical parameters with confidential test procedure was impossible. On these basis, a new part of KS is proposed, and some problems remained and further discussions in the proposed draft are described in this study.

• The Journal of the Acoustical Society of Korea
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• 제19권2호
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• pp.73-82
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• 2000

This paper presents a significant improvement achieved in the acoustic characteristics of a conference room of I-company originally designed and built without consideration for room acoustic characteristics. The reverberation time of the room was excessive, which resulted in poor 'Definition' for speech. Thus the improvement of room acoustic characteristics was required. In this study, experiments and simulations using the principles of geometrical acoustics were executed to improve the acoustic characteristics in the room. By performing a series of simulation, it has become possible to predict acoustic parameters for an improvement plan. And the improvement plan of room acoustic characteristics was established. And for the verification of the simulation results, the experimental data were compared and evaluated against those from the simulation. Additionally, the proposed method in this paper demonstrated its effectiveness by successfully improving the room acoustic characteristics resulted from repair construction.

• Journal of the Korean Institute of Educational Facilities
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• 제11권1호
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• pp.5-14
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• 2004

Since 1990s in Korea, elementary school classrooms have been designed toward open education system in pursuit of variety of educational purpose. Also, the architectural designs of schools have been acomplished for individual school not based on the standard design code. The present paper aims to investigate the acoustic environment of existing classrooms and to compare the sound insulation capacity between the ordinary classrooms and the newly built classrooms for open education. The current acoustical situation of elementary classrooms was analyzed using field measurements and questionnaire survey. In order to this, Three elementary schools were selected which were built in 1978, 1996 and 2000 respectively. Room acoustical parameters including Reverberation time(RT), Definition(D50), Speech Intelligibility(RASTI), Transmission loss(TL) and STC were measured in a classroom in each elementary school classroom. Each measurement was undertaken with the windows and doors being open or closed. As the result, it was found that the transmission loss between rooms in open classrooms is, $5{\sim}6dB$ in average, inferior than the ordinary classrooms. The RASTI of 0.70 was measured in newly built classrooms which is better than old classrooms(0.70) and open classrooms(0.73). This was shown as same in the speech definition measurements. This results from the condition of sealing and airtightness of classrooms and floor materials. The results denote that open classrooms have poor acoustic condition in sound insulation and speech intelligibility.