Q: How loud can music at a school disco be, and still be safe?

A: Excessive noise will permanently damage children’s delicate hearing, so it’s reasonable that parents worry about loud music at school discos. As the ‘dose’ of noise increases logarithmically, a small increase in volume leads to a rapid reduction in safe exposure time.

Loud music is not necessarily an unpleasant experience, but if you have to raise your voice or shout to be heard by a person at arm’s length, it’s definitely too loud. And obviously, if the volume is painful it needs to be turned down.

New Zealand’s laws protect people from excessive noise, primarily in the workplace. The regulations require that anyone with unprotected ears must not be exposed to a daily ‘noise dose’ exceeding an average 8 hours exposure at 85 decibels.

Noise levels double with each increase of 3 decibels, so the exposure level must be halved to maintain a safe dose. For example, 85 decibels over 8 hours is the same ‘dose’ as 88 over 4 hours, or 91 over 2 hours.

Adults who supervise school socials can use this calculation to determine a safe noise level. If a disco is to be two hours duration, the sound equipment should never be over 91 decibels. If for an hour, the maximum noise level could increase to 94 decibels. Just a small adjustment in volume can make all the difference between a safe and unsafe disco and still make the music enjoyable.

Google Play and the Apple App store have a number of sound level apps for smart phones., Adults supervising school socials can these to track and monitor live sound levels and intervene if necessary. Generally, speakers should have a two-metre clear area in front of them, and sound levels measured from this distance.

Adults who enjoy noisy pubs and clubs should keep a few rules in mind to safeguard their own hearing: if it hurts, or you have to shout to be heard, the venue is too loud. And If you end up with tinnitus, you’re potentially risking your hearing. As a safe noise dose depends on duration as well as volume, a day working in a noisy environment before going out in the evening will significantly reduce the noise dose that is safe for you.