Invesitigation And Evaluation Of Classroom Acoustical Environment In Elementary School

Classroom is a place of teaching and learning. The classroom acoustical environment isrelated to the quality of education and learning outcome.Methods of objective acoustic measurement and subjective questionnaire were employedto assess acoustical environment of10elementary schools in Guangzhou.Objective acoustic measurement procedures included noise pressure levels measurementin unoccupied classrooms, noise pressure levels and speech pressure levels measurementduring classes, and STI, C50, EDT and T30in classrooms. Subjective questionnaire was mainlyabout analyzing subjective feelings of students, teachers and parents towards classroomacoustical environment. The influences of noise on students and teachers and vocal health ofteachers were also investigated. Classroom acoustical environment on students’ intelligibilityfeeling and psychology were analysed. The relationship between subjective feelings andobjective acoustical parameters was discussed finally.Noise pressure level was47.1dBA in unoccupied classrooms. The noise pressure level inclassroom would be56.7dBA and56.2dBA respectively when using fans or opening windows.In class, teachers’ speech pressure level was70.7dBA and noise pressure level was61.5dBA,both of them would decrease with increase of students’ age and the dynamic range of themenlarged, but signal to noise ratio was10dBA. Range of EDT, T30,C50and STI in classroomswere0.98~1.34s,0.99~1.39s,-1.0~1.5dB and0.55~0.62, respectively. Results under differentmeasurement condition demonstrated STI and C50would increase together with the reduce ofEDT and T30when doors and windows were opened or curtain were used in classroom. STIand C50value in the position which was nearest to sound source would be the most affectedlocation when changing directions of sound source. Early reflected sound were lacked in thefront and middle place in classroom when plane of classroom was hexagon, as a result, theacoustical parameters in different position were in small difference.Questionnaire survey indicated that noise sources were traffic noise, adjacentclassrooms’noise, chatting among students in classroom, moving tables or chairs. The feelingsof students and teachers on noise were different. The chatting among surrounding classmateshad the most obvious impact on students, while teachers thought that noise out of school affected them most. Influence of noise on students’ feelings of intelligibility, annoyance andattention were considerable, especially, the feeling of intelligibility. There was better linearrelationship between noise pressure level and intelligibility feeling. The feeling ofintelligibility was inversely proportional to noise pressure level. Annoying threshold ofstudents in class was60.5dBA. As to teachers, noise would cause their annoyance, whatwould lower educational quality.