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2017 Vol.11, Issue 4 Preview Page
Measurements and Comparisons of Two Types of Combined Measures for Predicting Speech Intelligibility in University Classrooms

대학 강의실에서 언어 명료도를 평가하기 위한 두 가지 음향지표의 측정 및 비교

Young-Ji Choi1*
최 영지1*
1Division of Urban & Architecture, Kangwon National University
1강원대학교 도시건축학부 건축공학전공
*교신저자. *Corresponding Author. 
August 2017. pp. 295-304
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Abstract

The present study is a follow-up to previous paper titled “Prediction of changes to perceived reverberance due to added absorption by occupants in classrooms.” This work reports on the two types of combined measures, speech transmission index (STI) and useful-to-detrimental sound ratios (U50), for predicting speech intelligibility in university classrooms. Acoustical measurements were made in 12 occupied university classrooms. The measured impulse responses of the classrooms were used to determine the modulation transfer function, m(F), for the STI calculation according to IEC 60268-16. U50 values were determined by averaging octave band values from 125 to 4000 Hz and using the frequency weighting from the STI measure. The present results demonstrate that both measures, mean STI and frequency- weighted U50 values, were highly linearly related and essentially describe the same properties of the classrooms. The results showed that classrooms having U50 values of about +0.5 dB have STI values of 0.60, which indicates ‘Good’ acoustical conditions for speech intelligibility. The U50 measure can be more practically useful means of assessing and understanding real active classrooms.

Keywords
Speech intelligibility
Speech transmission index
Useful-to-detrimental sound ratios
University classrooms

키워드
언어 명료도
음성전달지수
초기 대 후기음에너지 비
대학 강의실
References
1
최영지. (2016). 재실자의 부가 흡음에 의한 강의실의 잔향감 변화 예측. 한국건축친환경설비학회논문집, 10, 375-380.
2
Bradley, J.S. (1986). Speech intelligibility studies in classrooms. J. Acoust. Soc. Am., 80, 846-854.
3
Bradley, J.S., Reich, R., Norcross, S.G. (1999). On the combined effects of signal- to-noise ratio and room acoustics on speech intelligibility. J. Acoust. Soc. Am. 1999, 106, 1820-1828.
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Bradley, J.S., Bistafa, S.R. (2002). Relating speech intelligibility to useful-to-detrimental sound ratios. J. Acoust. Soc. Am., 112, 27-29.
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Hodgson, M., Rempel, R., Kemmedy, S. (1999). Measurement and prediction of typical speech and background noise level in university classrooms during lectures. J. Acoust. Soc. Am., 105, 226-233.
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Hodgson, M., Nosal, E.M. (2002). Effect of noise and occupancy on optimal reverebration times for speech intelligibility in classrooms. J. Acoust. Soc. Am., 111, 931-939.
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Nijs, L., Rychtáriková, M. (2011). Calculating the optimum reverberation time and absorption coefficient for good speech intelligibility in classroom design using U50. Acta Acustica United with Acustica, 97(1), 93-102.
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Schroeder, M.R. (1981). Modulation transfer functions: Definition and Measurement. Acta Acustica United with Acustica, 49(3), 179-182.
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Sato, H., Bradley, J.S. (2008). Evaluation of acoustical conditions for speech commu-nication in working elementary school classrooms. J. Acoust. Soc. Am., 123, 2064-2077.
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Yang, W., Bradley, J.S. (2009). Effects of room acoustics on the intelligibility of speech in classrooms for young children. J. Acoust. Soc. Am., 125, 922-933.
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ANSI S3.5. (1997). American National Standard Methods for Calculation of the Speech Intelligibility Index. New York: American National Standards Institute.
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ANSI S12.60. (2004). Acoustics performance criteria, design requirements, and guidelines for schools. New York: American National Standards Institute.
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IEC 60268-16 Edition 4.0. (2011). Sound system equipment - Part 16: Objective rating of speech intelligibility by speech transmission index.
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ISO E 354-Acoustics. (2003). Measurement of sound absorption in a reverberation room.
Information
  • Publisher :Korean Institute of Architectural Sustainable Environment and Building Systems
  • Publisher(Ko) :한국건축친환경설비학회
  • Journal Title :Journal of Korean Institute of Architectural Sustainable Environment and Building Systems
  • Journal Title(Ko) :한국건축친환경설비학회논문집
  • Volume : 11
  • No :4
  • Pages :295-304
  • Received Date : 2017-06-06
  • Revised Date : 2017-08-29
  • Accepted Date : 2017-08-29
  • DOI :https://doi.org/10.12972/jkiaebs.20170003
Journal Informaiton Journal of Korean Institute of Architectural Sustainable Environment and Building Systems Journal of Korean Institute of Architectural Sustainable Environment and Building Systems
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