A set of mini traffic lights could signal the end of excessively noisy classrooms in primary schools.
The Safe Sound Indicator flashes green, amber then red to let pupils and teachers know when the racket reaches unacceptable levels.
It has already proved a success at significantly cutting noise in child centres across New Zealand.
Now primary schools are following suit to reduce the risk of hearing loss for children and their teachers and create an improved learning environment.
Torbay School is one of the first in Auckland to get a set of the indicators. More than 150 other primary schools will soon have them.
Torbay principal Wendy Sandifer said the lights have had an immediate impact.
"We have a number of children with mild to serious hearing issues and this system has really made a difference," she told the Herald on Sunday. "It is a lot more effective than having a teacher shout at everyone to pipe down.
"When the kids can physically see the noise is building up it makes them stop and think."
She added one of the teachers had some hearing difficulties and it was a valuable tool for him, too.
When the green light is on it means noise is below a safe level of 80 decibels. Amber indicates the sound is nearing levels which can cause hearing damage. Red means the reading has reached 90db - equivalent to the sound of a heavy truck going past.
When the devices - costing $292.50 apiece - were trialled in kindergartens, audio experts recorded some noise levels equivalent to a jet plane taking off.
The Safe Sound Indicator was developed over several years by the National Foundation for the Deaf from a concept by a 10-year-old girl, Jamie Fenton, from New Plymouth.
"The sound indicators are particularly effective in open-plan classrooms where noise can reach uncomfortable levels fairly quickly," Louise Carroll, chief executive of the Foundation for the Deaf, said.
"The classroom is where children learn by listening. The better they can hear, the easier it is for them to learn."
Carroll said 1200 had been snapped up by childcare centres and the instruments were also a valuable tool for reducing hearing damage. The foundation next plans to target noisy cafes and bistros.
Dr Stuart McLaren, senior lecturer in Environmental Health at Massey University, welcomed the visible sound indicators.
"You don't ask a child in a wheelchair or who has a physical disability to negotiate themselves up a flight of stairs, so why should we expect a hearing-sensitive child to navigate themselves around a noisy classroom? It can be very distressing," he said.By Russell Blackstock Email Russell