Abstract
The Chinese word identification and sentence intelligibility are evaluated
by grades 3 and 5 students in the classrooms with different reverberation
times (RTs) from three primary school under different signal-to-noise
ratios (SNRs). The relationships between subjective word identification
and sentence in- telligibility scores and speech transmission index (STI)
are analyzed. The results show that both Chinese word identification and
sentence intelligibility scores for grades 3 and 5 students in the
classroom in- creased with the increase of SNR (and STI), increased with
the increase of the age of students, and decreased with the increase of
RT. To achieve a 99% sentence intelligibility score, the STIs required for
grades 3, grade 5 students, and adults are 0.71, 0.61, and 0.51,
respectively. The required objective acoustical index determined by a
certain threshold of the word identification test might be underestimated
for younger children (grade 3 students) in classroom but overestimated for
adults. A method based on the sentence test is more useful for speech
intelligibility evaluation in classrooms than that based on the word test
for different age groups. Younger children need more favorable classroom
acoustical environment with a higher STI than older children and adults to
achieve the optimum speech communication in the classroom.
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