Noise-induced hear loss is on the rise amongst children as studies show listening to loud music can be just as addictive as smoking.
Dr David Welch, head of Auckland University's audiology department, says research shows about 14 per cent of children may have noise induced hearing loss as a result of prolonged exposure to personal listening devices.
Welch is speaking out as the Christmas holiday season is about to set in and children likely to be spending more time on their phones.
He's urging parents to keep an eye on their child's digital device use.
Welch says global studies show around 14 per cent of children may have noise induced hearing loss which could be a result of prolonged exposure to personal listening devices.
Noise-induced hearing loss is hearing impairment resulting from exposure to loud sound.
"People with this condition may have a measurable loss of hearing in a range of frequencies, but may also have impaired perception of sound in noisy environments, and this may occur alongside tinnitus, or ringing in the ears," he said.
Welch said change was needed at a societal level with better awareness of the permanent damage that was occurring.
"We can draw a parallel with smoking, which is also harmful behaviour, but one that as a society we're just not accepting anymore. We are much more tolerant of loud music even though we know it causes a permanent injury which can destroy our lives and cut us off from the people we care about," he said.
The maximum safe level for prolonged listening was considered to be 85 decibels - with most smartphones capable of producing volumes of up to about 120 decibels.
"The general trend appears to be that devices like smartphones are getting louder over time - with the latest model from one of the most popular brands capable of producing 25 per cent higher volume than its predecessor," he said.
When volume increases beyond 85 decibels, the threat to hearing rises and after two hours of listening to a device at 91 dB the child has incurred a similar level of exposure to working a shift in a noisy factory where hearing protection would be required by law, he said.
"Parents look at ways to limit the amount of time their children spend listening to loud music, whether it is in the car, at concerts or on devices."
He said there was a "cultural acceptance" of loud music.
"For kids there is a sense that listening to loud music is cool, and it makes them feel both part of a group but also they are able to lose themselves in it, it gives them a splendid isolation and a feeling of being able to cut themselves off from anything that's bothering them."
Welch says hearing was damaged through apoptosis where noise-damaged sensory cells in the inner ear will shut down and quietly kill themselves so they can't cause further harm.
"This process causes scarring which prevents new cells growing in their place. What's more, the nerve fibres that convey information from the ear to the brain are also thought to be threatened by exposure to loud sound.
"We are worried that this could become an epidemic of the digital generation - our children not aware of the potential impact and may be vulnerable to long term damage as a result."
Puro Sound Labs distributes children's headphones which automatically restrict maximum volume.
Owner Lee-Ann Verry said she began importing the product after becoming concerned about her own children's digital device use.
There was a growing understanding among parents and schools that there was a health risk associated with ongoing exposure to music at loud volumes, she said.
Lean budgets meant schools bought cheaper headphones resulting in poor sound meaning kids turn the volume right up.