The Primary Research On Middle And Small Size Classroom's Acoustical Environment

Classroom is the main places of teaching and learning. Good acoustics environment can guarantee the smooth communication and interaction between teachers and students, and improve the learning efficiency, make the teaching effect more effective, also be helpful for health of teachers.Speech intelligibility is the most important evaluation index in classroom acoustics environment. It is the main purpose of the acoustical design to obtain good speech intelligibility. Acoustical design in classroom should choose appropriate classroom shape, reasonable arrangement of the sound-absorbing material, and suitable noise control for optimal reverberation time and SNR, when necessary, use amplification equipment. After investigation, at present, the acoutics evnironment of classroom building exists such problems as reverberation time too long and the SPL in the rear of the large classroom too low, result in low speech intelligibility. While, some classrooms are failing to do enough noise control at the early design stage, the environment noise including traffic noise interference with normal teaching activities seriously. Using amplification equipment is an effective method to improve the classroom speech intelligibility, and one of the effective means to obtain good acousitcs environment for large classroom,.But for small classroom, using electronic devices increase investment cost, on the other hand, natural sound is more easily acceptable than electroacoustic, Too high loudness will make the visual and auditory incongruous. Improper arrangement in electronic devices perhaps cause"screaming", and the acoustic environmental deterioration.。Based on speech intelligibility as the main research object, the classroom acoustics environment by the natural vocal are discussed. Influence on speech intelligibility was researched from speech vocal characteristics, reverberation time ,SNR and early/late sound energy ratio. With the 3d simulation of indoor acoustic field and the practice investigation of classroom acoustic environment, research on the SNR, background, reverberation time , shape in the classroom acoustics environment and the volume limits with natural sound in middle-small size classroom of the general situation and the improvement on the classroom acoustics environment was discussed.