The Recent test measured the noise level created by the normal operation of a metal locker at 81 decibels. To put that into context, the American Tinnitus Association identified an alarm clock (2 feet away) as having a sound level of 80 db. Alternatively, the noise level is considered similar to that created by a washing machine.
In terms of reducing potential noise pollution in the indoor environment, specifying Duralife Lockers in a school corridor, instead of metal would create a material difference. It is the difference between a hallway filled with buzzing alarm clocks or a hallway filled with whooshing washing machines.