A study on the optimal English speech level for Chinese listeners in classrooms

Abstract Speech intelligibility in classrooms affects the learning efficiency of students directly, especially for the students who are using a second language. The speech intelligibility value is determined by many factors such as speech level, signal to noise ratio, and reverberation time in the rooms. This paper investigates the contributions of these factors with subjective tests, especially speech level, which is required for designing the optimal gain for sound amplification systems in classrooms. The test material was generated by mixing the convolution output of the English Coordinate Response Measure corpus and the room impulse responses with the background noise. The subjects are all Chinese students who use English as a second language. It is found that the speech intelligibility increases first and then decreases with the increase of speech level, and the optimal English speech level is about 71 dBA in classrooms for Chinese listeners when the signal to noise ratio and the reverberation time keep constant. Finally, a regression equation is proposed to predict the speech intelligibility based on speech level, signal to noise ratio, and reverberation time.

[1]  T Houtgast,et al.  A physical method for measuring speech-transmission quality. , 1980, The Journal of the Acoustical Society of America.

[2]  Leo L. Beranek,et al.  Noise and vibration control , 1971 .

[3]  Hiroshi Sato,et al.  Optimum speech level to minimize listening difficulty in public spaces. , 2007, The Journal of the Acoustical Society of America.

[4]  Murray Hodgson,et al.  Optimum Reverberation for Speech Intelligibility for Normal and Hearing-Impaired Listeners in Realistic Classrooms Using Auralization , 2007 .

[5]  A K Nábĕlek,et al.  Reception of consonants in a classroom as affected by monaural and binaural listening, noise, reverberation, and hearing aids. , 1974, The Journal of the Acoustical Society of America.

[6]  Tim Pring,et al.  Speech perception in noise by monolingual, bilingual and trilingual listeners. , 2010, International journal of language & communication disorders.

[7]  H. Fletcher.  The nature of speech and its interpretation , 1922 .

[8]  A K Nábĕlek,et al.  Perception of consonants in reverberation by native and non-native listeners. , 1984, The Journal of the Acoustical Society of America.

[9]  James Emil Flege,et al.  THE EFFECT OF EXPERIENCE ON ADULTS' ACQUISITION OF A SECOND LANGUAGE , 2001, Studies in Second Language Acquisition.

[10]  J. S. Bradley.  Predictors of speech intelligibility in rooms. , 1986, The Journal of the Acoustical Society of America.

[11]  Wim A. van Dommelen,et al.  Perception of English consonants in noise by native and Norwegian listeners , 2010, Speech Commun..

[12]  B. Moore,et al.  Frequency selectivity as a function of level and frequency measured with uniformly exciting notched noise. , 2000, The Journal of the Acoustical Society of America.

[13]  F. Aigner,et al.  On a Physiological Effect of Several Sources of Sound on the Ear and Its Consequences in Architectural Acoustics , 1935 .

[14]  J. S. Bradley,et al.  Reverberation time and maximum background-noise level for classrooms from a comparative study of speech intelligibility metrics. , 2000, Journal of the Acoustical Society of America.

[15]  Masayuki Morimoto,et al.  Acceptable range of speech level in noisy sound fields for young adults and elderly persons. , 2011, The Journal of the Acoustical Society of America.

[16]  J. M. Pickett,et al.  Effects of Vocal Force on the Intelligibility of Speech Sounds , 1956 .

[17]  Xiaojun Qiu,et al.  Speech intelligibility with speech level at constant signal to Noise Ratio , 2013 .

[18]  W. T. Nelson,et al.  A speech corpus for multitalker communications research. , 2000, The Journal of the Acoustical Society of America.

[19]  J. S. Bradley,et al.  Speech intelligibility studies in classrooms. , 1986, The Journal of the Acoustical Society of America.

[20]  Anne Cutler,et al.  Non-native speech perception in adverse conditions: A review , 2010, Speech Commun..

[21]  T. Houtgast.  The effect of ambient noise on speech intelligibility in classrooms , 1981 .

[22]  Irwin Pollack,et al.  Masking of Speech by Noise at High Sound Levels , 1958 .

[23]  J. S. Bradley,et al.  The intelligibility of speech in elementary school classrooms. , 2008, The Journal of the Acoustical Society of America.

[24]  J. Ahlstrom,et al.  Recognition of filtered words in noise at higher-than-normal levels: decreases in scores with and without increases in masking. , 2005, The Journal of the Acoustical Society of America.

[25]  L. Robles,et al.  Basilar-membrane responses to tones at the base of the chinchilla cochlea. , 1997, The Journal of the Acoustical Society of America.

[26]  Densil Cabrera,et al.  Effect of listening level and background noise on the subjective decay rate of room impulse responses: Using time-varying loudness to model reverberance , 2010 .

[27]  David M. Howard,et al.  Acoustics and Psychoacoustics , 2006 .

[28]  K. D. Kryter.  Effects of Ear Protective Devices on the Intelligibility of Speech in Noise , 1946 .

[29]  Murray Hodgson,et al.  Rating, ranking, and understanding acoustical quality in university classrooms. , 2002, The Journal of the Acoustical Society of America.

[30]  Murray Hodgson,et al.  Auralization study of optimum reverberation times for speech intelligibility for normal and hearing-impaired listeners in classrooms with diffuse sound fields. , 2006, The Journal of the Acoustical Society of America.

[31]  Peng Jian-xin,et al.  Chinese speech intelligibility at different speech sound pressure levels and signal-to-noise ratios in simulated classrooms , 2010 .

[32]  J.P.A. Lochner,et al.  The influence of reflections on auditorium acoustics , 1964 .