The intelligibility of speech in elementary school classrooms

Abstract

This is the second of two papers describing the results of acoustical measurements and speech intelligibility tests in elementary school classrooms. The intelligibility tests were performed in 41 classrooms in 12 different schools evenly divided among grades 1, 3, and 6 students (nominally 6, 8, and 11 year olds). Speech intelligibility tests were carried out on classes of students seated at their own desks in their regular classrooms. Mean intelligibility scores were significantly related to signal-to-noise ratios and to the grade of the students. While the results are different than those from some previous laboratory studies that included less realistic conditions, they agree with previous in-classroom experiments. The results indicate that +15 dB signal-to-noise ratio is not adequate for the youngest children. By combining the speech intelligibility test results with measurements of speech and noise levels during actual teaching situations, estimates of the fraction of students experiencing near-ideal acoustical conditions were made. The results are used as a basis for estimating ideal acoustical criteria for elementary school classrooms.

Chinese Word Identification and Sentence Intelligibility in Primary School Classrooms

“…Moreover, in the classroom it is more critical for children to clearly identify a sentence and to understand its meaning, than to recognize the single word. The method that required objective acoustical index (such as STI and SNR(A)) for different age group were determined by a 95% word identification score (Bradley, Sato, 2008;Astolfi et al, 2012;Peng et al, 2015), might not be optimal for children in classrooms. A certain threshold based on the sentence intelligibility score for different age groups to determine the required objective acoustical index may be more objective and practicable.…”

“…The grade 3 and 5 students would need a 0.2 and 0.1 greater STI value to obtain the same sentence intelligibility scores as the adults. For word tests, Bradley and Sato (2008) pointed that a word identification score of 95% correct is used to indicate near-ideal conditions. According to Fig.…”

“…Background noise, reverberation time and SNR all have a critical impact on speech communication in the classroom. Many studies had investigated speech intelligibility in classrooms (Bradley, 1986;Houtgast, 1981;Bradley, Sato, 2008;Tang, Yeung, 2004;Brachmanski, 2008;2012;Astolfi et al, 2012, Peng et al, 2015 and the relationship between speech intelligibility scores and objective acoustical indices, such as speech transmission index (STI), A-weighted signal-to-noise ratio (SNR(A)) and useful/detrimental sound ratio for different language (Houtgast, 1981;Bradley, 1986;Anderson, Kalb, 1987;Brachmański, 2004;Peng et al, 2015). Houtgast (1981) conducted a series of speech intelligibility tests in classrooms for teachers and children aged 8 to 15 years under a variety of road traffic noise conditions with reverberation times (RTs) from 0.7 s to 1.5 s. The relationship between SNR(A) and speech intelligibility scores for Dutch was reported.…”

Acoustics of Classrooms in Primary Schools - Results of the Reverberation Time and the Speech Transmission Index Assessments in Selected Buildings

“…In the currently used criteria, defined using research conducted on adults, "good" refers to the speech transmission index value STI ≥ 0.6 (Table 2). Bradley and Sato (2008) claim that children attending classes in primary schools, learning new words and terms, have significantly lower speech understandability than adults; therefore, the authors have assumed a minimum speech transmission index value STI dop = 0.70 (similarly to the value defined for class C classrooms in the Finnish standard SFS 5907:en, Table 3). Table 4 presents separately for form 0-III classrooms and form IV-VI classrooms and for each primary school (A, B, C, D, E): the number of classrooms, mean room volume in the school, mean reverberation times T mf,mean and T wf,mean of rooms in the school including standard deviation.…”

Sound localization and word discrimination in reverberant environment in children with developmental dyslexia

“…Alterations of auditory information localization, in reverberant environment may influence a wide range of communication processes of children in classrooms 17 . With the objective to obtain an optimal percentage of adequate speech intelligibility in the classroom, noise levels must be controlled, and thus time of reverberation (TR) must be adequate 18,19 .…”