The claim is made in a British Journal of Psychiatry study.
The published findings suggest that, in most cases, the auditory hallucinations stop with time.
However, children who continue to hear voices could be at risk of mental illness or behavioural disorders.
Researchers carried out psychiatric assessments of almost 2,500 children aged between 11 and 16 in both school-based surveys and in-depth interviews around the country.
They discovered that 21%-23% of younger adolescents, aged 11 to 13, had experienced auditory hallucinations.
Of this group, slightly over half were found to have a non-psychotic psychiatric disorder such as depression.
Just 7% of older adolescents aged 13 to 16 reported hearing voices - but almost 80% of those who did had a diagnosable psychological problem.
Lead researcher on the paper, Dr Ian Kelleher, from the Department of Psychiatry at the Royal College of Surgeons in Ireland (RCSI), said: "Auditory hallucinations can vary from hearing an isolated sentence now and then, to hearing 'conversations' between two or more people lasting for a several minutes."
But he cautioned against undue alarm on the part of parents saying: "For many children, these experiences appear to represent a 'blip' on the radar that does not turn out to signify any underlying or undiagnosed problem.
"However, for the other children, these symptoms turned out to be a warning sign of serious underlying psychiatric illness, including clinical depression and behavioural disorders, like attention deficit hyperactivity disorder."
Co-author Professor Mary Cannon, also from the RCSI's Department of Psychiatry, said: "Our study suggests that hearing voices seems to be more common in children than was previously thought."
More than one in five Irish children between 11 and 13 have reported hearing voices, a sign some experts believe is a risk factor in mental illness.