The literature to date on noise in school rooms appears to focus on the effects on schoolchildren in general, their teachers and the hearing impaired.

The more sleep spindles your brain produces, the more likely you'll stay asleep, even when confronted with noise, " said Jeffrey Ellenbogen of Harvard Medical School in Boston.

Usually at the beginning of school, the noise of desks being opened and closed, and lessons repeated at the top of the children "s voices could be heard out in the street."