School noise detrimental to hearing and learning

The collective sound of human voices is the greates noise problem in schools, according to noise level measurements. The noise from multiple voices is significantly louder than machinery or other equipment.

Pupils talk loudly among each other, one-to-one or in group settings. Yelling and screaming can expose pupils and teachers to dangerous noise levels as high as 130 dB, sometimes resulting in permanent hearing damage.

Teachers modulate their voices according to the background noise. And a general problem is pupils and teachers trying to make themselves heard over each other instead of keeping the noise down and speaking in turn.

In a normal classroom setting the teacher's voice is some 20-30 dB above the background noise level. For example, a teacher's voice level was measured at 50-60 dB in a classroom with a bacground noise level measured at 33 dB. The louder the background noise, the louder the teacher must speak, and this, in turn, may result in increased background noise.

Examples of average measurements of background noise levels in school settings:

Ordinary classroom: Background noise level with 17 pupils engaged in group work, 45-50 dB.
Background noise i unruly classroom with 11 students engaged in group work, 60-65 dB.
Child grabbing for lego blocks in box (measured from distance of1 meter), 82 dB.
Two children talking about toys (measured from distance of 2 meters), 78-82 dB.
Bell in hallway (peak value measured from distance of 2 meters), 115 dB.
Music class: Pupils talking (background noise without music), 68-73 dB.
School kitchen: Pupils talking and cooking (background noise without machinery noise), 67-80 dB.
Wood working room: Pupils talking and working (background noise without power tool noise), 78-90 dB.

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