Common acoustic concerns in schools
Classroom reverberation is excessive, making it difficult to hear the teacher's talk.

Inspection and measurement
Classrooms are built on a concrete construction with P-tile interior finishing and a mostly painted finish, meaning no sound-absorbing material was used. As such, when measuring the reverberation time to analyze the sound field of the classroom, the reverberation time was longer than the appropriate range.
Cause and remedy
Because almost no sound-absorbing material is used, conversation clarity is low due to the long reverberation time. The walls are built with windows, so installing sound-absorbing material on the ceiling is one general countermeasure, but installation of sound-absorbing material on walls facing the teacher is desirable.
Speeches on the auditorium are difficult to hear.

Inspection and measurement
Lectures given on the auditorium stage of a school can be difficult to hear from both the speaker and the listener.
The auditorium used wooden grating designs for ceilings and walls made of windows and gypsum board finishing. Even with the 25 mm of sound-absorbing material used on the back wall, voices from the stage were difficult to hear. Reverberation time and impulse response measurements were conducted to investigate the room acoustics.
Cause and remedy
Even though sound-absorbing material is used, the sound field causes a strong echo from the rear wall during lectures from the stage. Loudspeakers distributed along the side walls are reflected to the speaker on the stage, resulting in numerous echoes in the front audience seats, making it difficult to hear.
Examination of the sound-absorbing material on the rear wall showed that the vinyl wallpaper with needle hole patterns used as the surface material offered insufficient sound absorption. Suggested countermeasures included changing to 50 mm thick glass fiber wallpaper with a higher sound absorption coefficient and adjusting the volume of the distributed loudspeakers.
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