Intelligibility of Reverberant Speech with Amplification: Limitation of Speech Intelligibility Metrics, and a Preliminary Examination of an Alternative Approach
This study examines the effect
of speech level on intelligibility in different reverberation conditions, and
explores the potential of loudness-based reverberation parameters proposed by
Lee et al. [J. Acoust. Soc. Am., 131(2), 1194-1205 (2012)] to explain the
effect of speech level on intelligibility in various reverberation conditions.
Listening experiments were performed with three speech levels (LAeq of 55 dB,
65 dB and 75 dB) and three reverberation conditions (T20 of 1.0 s, 1.9 s and
4.0 s), and subjects listened to speech stimuli through headphones. Collected
subjective data were compared with two conventional speech intelligibility
parameters (Speech Intelligibility Index and Speech Transmission Index) and two
loudness-based reverberation parameters (EDTN and TN). Results reveal that the
effect of speech level on intelligibility changes with a room’s reverberation
conditions, and that increased level results in reduced intelligibility in
highly reverberant conditions. EDTN and TN explain this finding better than do
STI and SII, because they consider many psychoacoustic phenomena important for
the modeling of the effect of speech level varying with reverberation.
References
[1]
ISO 3382-1 (2009) Acoustics—Measurement of Room Acoustic Parameters—Part I: Performance Spaces. International Organization for Standardization.
[2]
IEC 60268-16 (2011) Sound System Equipment—Part 16: Objective Rating of Speech Intelligibility by Speech Transmission index. International Electrotechnical Commission.
[3]
ANSI S3.5 (1997) Methods for Calculation of the Speech Intelligibility Index. American National Standard.
[4]
Fletcher, H. (1922) The Nature of Speech and Its Interpretation. Bell Labs Technical Journal, 1, 129-144.
http://dx.doi.org/10.1002/j.1538-7305.1922.tb00384.x
[5]
Kryter, K.D. (1946) Effects of Ear Protective Devices on the Intelligibility of Speech in Noise. Journal of the Acoustical Society of America, 18, 413-417. http://dx.doi.org/10.1121/1.1916380
[6]
Pollack, I. and Pickett, J.M. (1958) Masking of Speech by Noise at High Sound Levels. Journal of the Acoustical Society of America, 30, 127-130. http://dx.doi.org/10.1121/1.1909503
[7]
Hagerman, B. (1982) Sentences for Testing Speech Intelligibility in Noise. Scandinavian Audiology, 11, 79-87.
http://dx.doi.org/10.3109/01050398209076203
[8]
Lee, D. and Cabrera, D. (2010) Effect of Listening Level and Background Noise on the Subjective Decay Rate of Room Impulse Responses: Using Time-varying Loudness to Model Reverberance. Applied Acoustics, 71, 801-811.
http://dx.doi.org/10.1016/j.apacoust.2010.04.005
[9]
Lee, D., Cabrera, D. and Martens, W.L. (2012) The Effect of Loudness on the Reverberance of Music: Reverberance Prediction Using Loudness Models. Journal of the Acoustical Society of America, 131, 1194-1205.
http://dx.doi.org/10.1121/1.3676602
[10]
Glasberg, B.R. and Moore, B.C.J. (2002) A Model of loudness Applicable to Time-Varying Sound. Journal of the Audio Engineering Society, 50, 331-342.
[11]
Chalupper, J. and Fastl, H. (2002) Dynamic Loudness Model (DLM) for Normal and Hearing-Impaired Listeners. Acta Acustica United with Acustica, 88, 378-386.
[12]
Poulsen, T. (1981) Loudness of Tone Pulses in a Free Field. Journal of the Acoustical Society of America, 69, 1786- 1790. http://dx.doi.org/10.1121/1.385915
[13]
Sone, T., Suzuki, Y., Kumagai, M. and Takahashi, T. (1986) Loudness of a Single Burst of Impact Sound: Results of Round Robin Tests in Japan (I). Journal of the Acoustical Society of Japan, 7, 173-182.
http://dx.doi.org/10.1250/ast.7.173
[14]
Florentine, M., Buus, S. and Poulsen, T. (1996) Temporal Integration of Loudness as Function of Level. Journal of the Acoustical Society of America, 99, 1633-1644. http://dx.doi.org/10.1121/1.415236
[15]
Stevens, S.S. (1955) The Measurement of Loudness. Journal of the Acoustical Society of America, 27, 815-829.
http://dx.doi.org/10.1121/1.1908048
[16]
Schroeder, M.R. (1965) New Method of Measuring Reverberation Time. Journal of the Acoustical Society of America, 37, 409-412. http://dx.doi.org/10.1121/1.1909343
[17]
Moore, B J.C. and Glasberg, B.R. (2007) Modeling Binaural Loudness. Journal of the Acoustical Society of America, 121, 1604-1612. http://dx.doi.org/10.1121/1.2431331
[18]
AS 2282 (1985) Acoustics—Methods of Assessing and Predicting Speech Privacy and Speech Intelligibility. Australian Standard.
[19]
Cabrera, D., Lee, D., Yadav, M. and Martens, W.L. (2011) Decay Envelope Manipulation of Room Impulse Responses: Techniques for Auralization and Sonification. Proceedings of Acoustics, Gold Coast, 2-4 November 2011, CD-ROM.
[20]
Cabrera, D., Jimenez, D. and Martens, W.L. (2014) Audio and Acoustical Response Analysis Environment (AARAE): a Tool to Support Education and Research in Acoustics. Proceedings of Internoise, Melbourne, 16-19 November 2014, CD-ROM.
[21]
Cabrera, D., Lee, D., Leembruggen, G. and Jimenez, D. (2014) Increasing Robustness in the Calculation of the Speech Transmission Index. Building Acoustics, 12, 181-198. http://dx.doi.org/10.1260/1351-010X.21.3.181
[22]
Bradley, J.S., Reich, R. and Norcross, S.G. (1999) A Just Noticeable Difference n C50 for Speech. Applied Acoustics, 58, 99-108. http://dx.doi.org/10.1016/S0003-682X(98)00075-9
[23]
Studebaker, G.A., Sherbecoe, R.L., McDaniel, D.M. and Gwaltney, C.A. (1999) Monosyllabic Word Recognition at Higher-Than-Normal Speech and Noise Levels. Journal of the Acoustical Society of America, 105, 2431-2444.
http://dx.doi.org/10.1121/1.426848
[24]
Morimoto, M., Sato, H. and Kobayashi, M. (2004) Listening Difficulty as a Subjective Measure for Evaluation of Speech Transmission Performance in Public Spaces. Journal of the Acoustical Society of America, 116, 1607-1613.
http://dx.doi.org/10.1121/1.1775276
