How loud is too loud when it comes to sports whistles?

Referees and others using whistles on the job need a simple way to determine whether it’s harmful to their hearing, so researchers set out to put it to the test and to provide some clarity and damage risk criteria for impulse noise exposures. To do this, the group carefully measured and analyzed the acoustic signature of 13 brands of whistles identified as the ‘most commonly used’ by 300 sports officials — both indoors and outdoors.
Source: EurekaAlert, https://www.eurekalert.org