Developing statistical acoustics model for lecture auditorium using application of reverberation time

Abstract

This article focusses on the findings of a research project into the acoustic characteristics of University Tun Hussein Onn Malaysia (UTHM) classrooms. The listening ability of the students in different sitting positions with different classrooms design was conducted. Physical measurements were taken from 10 sample rooms of lecture halls and normal classrooms in four different conditions; when occupied, unoccupied, with and without air-conditioning. For an optimal learning environment in terms of Speech intelligibility of selected theatre halls and normal classrooms, academic building block G3 of UTHM have been analyzed experimentally and analytically using survey questionnaires, direct measurements of classroom noise levels and reverberation time. Thus, a statistical approach was performed to estimate the reverberation time in a room. Reverberation time and sound pressure level were correlated and the linear regression analysis was executed. The analysis was carried out using SPSS software. The survey identified the lecture auditoriums that were acoustically rated by both lecturers and students as either good or bad. The result obtained from direct measurements shows that the 'good' classrooms when occupied typically had a mid-frequency (average of 500 Hz & 1 kHz) reverberation time (RT) of 0.42 seconds. The mid-frequency reverberation time in the “poor rooms” ranged from 0.53 to 0.63 seconds, while when unoccupied the 'good' classrooms typically had a mid-frequency reverberation time (RT) of 0.47 seconds. The mid-frequency reverberation time in the “poor rooms” ranged from 0.59 to 0.67 seconds. It's obvious that theatre halls are having better acoustic properties and there was a good agreement with the result obtained from the survey. The result from the statistical models shows that the predicted reverberation time was reliable with an average percentage of errors of less than 18% compared to the measured reverberation time.