Evaluation of acoustical conditions for speech communication in working elementary school classrooms

Abstract

/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/10.1121/1.2839283Journal of the Acoustical Society of America, 123, 4, pp. 2064America, 123, 4, pp. -2077America, 123, 4, pp. , 2008 Evaluation of acoustical conditions for speech communication in working elementary school classrooms Sato, H.; Bradley, J. S. The purpose of the work was to better understand how to improve speech communication between teachers and students. The study found that on average the students experienced:teacher speech levels of 60.4 dBA, noise levels of 49.1 dB and a mean speech-to-noise ratio of 11dBA during teaching activities. The mean reverberation time in the occupied classrooms was 0.41 s, which was 10% less than in the unoccupied rooms. The reverberation time measurements were used to determine the average absorption added by each student. Detailed analyses of early and late-arriving speech sounds showed these sound levels could be predicted quite accurately and suggest improved approaches to room acoustics design.

Effects of source-to-listener distance and masking on perception of cochlear implant processed speech in reverberant rooms

“…Unnormalized speech levels at each position for a 65 dBA direct field at 1 m are shown in Table IV. Level differences were, as in experiment 1, consistent with theoretical predictions ͑Barron and Lee, 1988;Sato and Bradley, 2008͒. It should be noted that without SPL normalization listeners in rooms with ␣ = 0.7 or ␣ = 1.0 could receive speech at levels near 50 dB SPL, a level that has been shown to impair intelligibility for implant users ͑Skinner et al Firszt et al, 2007͒.…”

“…For anechoic speech of 65 dBA at 1 m, measured speech levels at the 1, 3, and 4 m positions were 67.7, 64.8, and 63.5 dBA, respectively. These small differences in level as a function of SLD are consistent with theoretical predictions for a classroom of this size ͑Barron and Lee, 1988; Sato and Bradley, 2008͒. All speech signals were subsequently presented to the subjects at 65 dBA, with the level held constant to differentiate the effects of reflection patterns at each position from any effects of level difference.…”

“…Further, for those users who are bilaterally implanted, uncoordinated input to the two clinical speech processors could impose limitations on the use of cues that would result in the ability to suppress noise in favor of speech ͑i.e., the "binaural squelch" effect͒ and other expected speech-in-noise improvements afforded to listeners with binaural hearing ͑MacKeith and Coles, 1971͒. Finally, it is also possible that CI users might benefit from spatial differences in early reflection patterns, which have been shown to increase the effective signal level and improve intelligibility in some situations ͑Barron and Lee, 1988;Yang and Hodgson, 2006;Sato and Bradley, 2008͒. This possibility will be explored in future investigations.…”

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

“…They also proposed a method for estimating SNR values in classrooms when they are occupied and in operation. The results of the active classroom acoustics studies (Hodgson et al, 1999;Sato, Bradley, 2008) indicate greater noise levels than recommended in the ANSI standard for classroom acoustics (ANSI S12.60, 2004).…”

“…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. They also proposed a method for estimating SNR values in classrooms when they are occupied and in operation.…”