Effects of background noise on speech intelligibilityin elementaryschool classrooms in Dhaka city

Abstract

Acousticsis a significant role player for creating an environment ensuring hearing and performance. Poor classroom acoustics can create a negative learning environment for many students. In elementary school classrooms, a proper acoustic environment is a prime necessity to promote learning, psycho-physical development and to maintain hearing health of students particularly at their early age. This appropriate acoustic environment is also essential for teachers and staffs working in the school for performing their best. Noise levelsin Dhaka city, particularly in areas closer to major roads and nodes, are beyond the acceptable limit as recommended by national codes. On the other hand, a proper acoustic design of classrooms is missing in many cases. As a result, unacceptable noise level, Reverberation Time, speech level, speech diffusion and speech privacy are prevalent in those classrooms. Unacceptable level of background noise and Reverberation Time reduces speech intelligibility and compromise psycho-educational and social development of students. This study explores the prevailing situation of speech intelligibility of Bangla medium elementary school classrooms in Dhaka city. As a part of the methodology, surveyswere conducted on some Bangla medium elementary school classrooms in Dhaka city to understand the present acoustic condition,in terms of speech intelligibility. Based on reconnaissance survey, ten classrooms (where main communication source is Bangla language) from two schools have been chosen for Percentage Syllable Articulation (PSA) test. The sample listeners (students) were screened for good hearing health through audiometric test. PSA results are analysed using computer software to checkcorrelations betweenbackground noise level and PSA, and again between Reverberation Timeand PSA, for testing hypothesis.Analysis shows that the high background noise play a significantrole in decreasing PSA of the students and thus resulting low level of intelligibility. The study finally demonstratesthe prevailing poor condition of speech intelligibility of elementary school classroomsinDhaka city.