One reason for this seeming "epidemic" in hearing impairment is the huge amount of noise pollution in the modern world.
How noisy is your school? It is often left to guesswork or an institution - until now.
Soundship aps, a Danish firm, has produced a reliable and scientific way to monitor changing levels of noise.
A small device logs the noise level every five minutes over a period of up to four weeks.
Data is stored in a small box which can then be removed and attached to a PC for downloading.
Results can be printed in graph form so that you can see how sound levels fluctuate hourly or daily. The firm says schools can easily check the noisiest times of day and estimate the risk of noise pollution to pupils and staff.
SoundLog builds on the company's existing product, SoundEar, which won the Danish Design Award in 2000.
Today, these small devices hang on the walls of thousands of workplaces and schools in Denmark.