Effect of noise and occupancy on optimal reverberation times for speech intelligibility in classrooms

Hodgson, Murray; Nosal, Eva‐Marie

doi:10.1121/1.1428264

Cited by 82 publications

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“…Hodgson [10] carried out speech intelligibility tests by auralizing virtual sound fields to support the earlier work [9]. Although they were largely successful, they did not give the actual signal-to-noise ratios of their conditions and they made no attempt to confirm that their conditions would represent the balance between early-and late-arriving sounds that would commonly occur in real rooms.…”

Section: Introductionmentioning

confidence: 99%

“…However, it has at other times been argued that increased reflected sound would increase both speech and noise levels and would result in no change to S/N values. Hodgson and Nosal [9] have explained that what is critical is the relative distances of the speech and noise sources from the listener. Their calculations, based on simple diffuse field theory, showed that when the noise source is closer to the listener than the talker, then added early reflections would usefully increase S/N values and hence would be expected to improve speech intelligibility.…”

Section: Introductionmentioning

confidence: 99%

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Effects of room acoustics on the intelligibility of speech in classrooms for young children

Yang

Bradley²

2009

The Journal of the Acoustical Society of America

146

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/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1121/1.3058900Journal of the Acoustical Society of America, 125, 2, pp. 1-12, 2009-02-01 Effects of room acoustics on the intelligibility of speech in classrooms Yang, W.; Bradley, J. S.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of room acoustics on the intelligibility of speech in classrooms for young children

Yang

Bradley²

2009

The Journal of the Acoustical Society of America

146

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“…Classroom quality was strongly correlated with the background noise level and the related signal-to-noise ratios (Hodgson, 2002), emphasising the need for the design criteria for occupied classrooms (Hodgson, Nosal, 2002). A number of studies (Hodgson et al, 1999;Sato, Bradley, 2008) have reported that the speech and noise levels are quite different from values measured in active classrooms with the influence of noise due to students' activity.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Two Types of Combined Measures, STI and U50, for Predicting Speech Intelligibility in Classrooms

Choi

2017

Archives of Acoustics

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The present study reports on the speech intelligibility as measured by speech transmission index (STI) and useful-to-detrimental sound ratios (U50) in university classrooms. Acoustic measurements were made in 12 quietly 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 from both signal-to-noise ratios (SNR) and C50 values. The mean STI and frequency-weighted U50 values for the 12 occupied classrooms were strongly linearly related. The results showed that classrooms with U50 values of about +0.5 dB correspond to STI values of 0.60, indicating 'good' acoustical conditions for speech intelligibility. The results illustrate that the U50 measure can be a more practically useful means of assessing and understanding room acoustics conditions for real speech communication in active classrooms.

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Section: Introductionmentioning

confidence: 99%

“…Noise is also affected by the reverberation time, as are the speech levels. Thus, the spatial relationship between a listener and the sound sources -both speech and noiseaffects the optimal reverberation for speech intelligibility in rooms [1].In this project, an experimental approach to identify the optimal reverberation time in an idealized room, and validate theoretical prediction, considering babble noise sources inside the room, is presented using auralization. Realistic optimal reverberation times are found using speech-intelligibility tests with normal-hearing and hard-ofhearing subjects.…”

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confidence: 99%

Investigation of the optimum acoustical conditions for speech using auralization

Yang

Hodgson

2004

The Journal of the Acoustical Society of America

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i n t r o d u c t i o nSpeech intelligibility is known to be mainly determined by the signal-to-noise level difference at a listener, and reverberation. It is directly related to signal-tonoise level difference and is inversely related to the reverberation time. However, their interaction results in a complicated situation in real rooms. Increased reverberation benefits speech intelligibility by increasing speech levels. Noise is also affected by the reverberation time, as are the speech levels. Thus, the spatial relationship between a listener and the sound sources -both speech and noiseaffects the optimal reverberation for speech intelligibility in rooms [1].In this project, an experimental approach to identify the optimal reverberation time in an idealized room, and validate theoretical prediction, considering babble noise sources inside the room, is presented using auralization. Realistic optimal reverberation times are found using speech-intelligibility tests with normal-hearing and hard-ofhearing subjects. The best metric predicting speech intelligibility is presented for both normal-hearing and hardof-hearing groups. METHOD SubjectsSubject groups for the study were normal-hearing and hard-of-hearing people with a mild to moderate sensori neural hearing loss. The hearing-loss criterion for the hardof-hearing subjects was less than 20 dB at 250 Hz and 500 Hz and greater than 30 dB at 1 kHz to 8 kHz. Twenty-four normal-hearing subjects (mean age=27) and ten hard-ofhearing subjects (mean age=58) completed the tests. Test materials and simulated sound fieldsThe Modified Rhyme Test (MRT) was used as the speech-intelligibility test. The MRT lists were processed through the CATT-Acoustics room-acoustical prediction and auralization program with 4-talker babble noise The volume of the virtual room used for the simulation was 385 m3 (11 m x 7 m x 5 m). Fig. 1 shows the elevation of the virtual room, and the relative positions of the listener, the speaker, and the noise sources. In this study, the object was to model an idealized room with exponential sound decay. The effects of the different distributions of various surface materials on the walls, floor and ceiling were excluded by using the same absorption coefficients and diffusion coefficients for all octave bands and for all of the surfaces.A total of 16 different sound fields were created, consisting of the combinations of 2 different speech-and noise-source output levels (SNS = 0 and +5 dB), 4 different reverberation times (RT = 0, 0.2, 0.4, and 0.8 s), and 2 different positions of the noise source (see Fig. 1). The speech-to-noise level difference at the listener (SNR) varied from -6 dB to 8.5 dB.The completed auralization test materials were transferred to a compact disc for presentation using a CD player. Hearing screening tests were done prior to the main speech-intelligibility test to identify the hearing categories of subjects. The tests were processed through a Sony MDR V600 headphone in a soundproof room. RESULTSFig . 2 shows the mean speech-intellig...

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Effect of noise and occupancy on optimal reverberation times for speech intelligibility in classrooms

Cited by 82 publications

References 8 publications

Effects of room acoustics on the intelligibility of speech in classrooms for young children

Effects of room acoustics on the intelligibility of speech in classrooms for young children

Comparison of Two Types of Combined Measures, STI and U50, for Predicting Speech Intelligibility in Classrooms

Investigation of the optimum acoustical conditions for speech using auralization

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