About one third of teachers missed one day of work each year because of a problem with their voice, although a very small proportion had received voice training or treatment.
While there were no major differences between male and female teachers in the severity of problems, it took women longer to recover.
Female teachers aged between 51 and 60 were at most risk of developing a voice problem - although those older than 60 were less likely to report a voice problem during their career than younger teachers.
The study authors suggested it was possible that those who had remained in class beyond 60 may have been able to do so because of their "robust voices".
Primary school teachers were more likely to report voice problems than secondary school teachers, which may have been due to a curriculum that called for more interaction with students.
"A further reason may be that younger children require more attention and interaction."
They concluded most teachers with voice problems did not seek health support and weren't aware of the potential risks, or what support was available. "Preventative and tailored treatment programmes for New Zealand teachers are clearly needed."
Auckland head and neck surgeon Dr David Vokes, who counted teachers among his most common clients, felt there wasn't enough support in schools.
By the numbers
• 1081 of 1879 surveyed primary and secondary teachers reported voice problems of some sort in their careers.
• 36.5% reported moderate problems, with a further 10.9% severe or very severe, and 52.5% mild or very mild.
• 7% reported chronic problems needing at least four weeks recovery time; 70.5% required less than a week to recover.
• 22.4% had sought health assistance for voice problems.
Using it without losing it
After 32 years in the classroom - and many days off work with a sore throat - Jackie Dodd wished she'd known about the risk of voice problems when she started teaching.
"I would have definitely benefited from specialist help and advice about how to look after my voice and how to project it safely," the teacher at Te Wharau School in Gisborne said.
Ms Dodd suffers laryngitis between five and six times a year, leaving her unable to speak and at times away up to seven days.
Unlike many of the teachers surveyed by University of Auckland researchers, Ms Dodd has sought help through medicine and speech language therapy.
"I'm very aware of how I use my voice and avoid situations where I have to project it for long periods of time," she said. "I also moderate my volume and projection so as not to strain my voice."
But there were many situations where teachers found themselves straining their voices, such as speaking above wind and background noise when taking outdoor physical education classes.
The Ministry of Education's deputy secretary of student achievement, Graham Stoop, said while the study was of interest to the ministry, the day-to-day welfare of teachers was a matter for individual school boards.
NZEI national president Louise Green said it appeared to be an under-reported and "largely overlooked problem".
"Many schools also use a voice amplification system in the classroom and I would support that - of course, that is a resource issue for schools and there are many competing demands on school budgets."
