Pure-tone auditory thresholds in children are below the standardized hearing threshold levels described by ISO 7029 (2000). The development of hearing ability in Chinese and German children at different ages is analyzed and compared with data in the literature. Extended high frequencies above 8 kHz are included due to their vulnerability to noise.
Ninety-one children in China and 197 children at a typical primary school in Germany underwent audiometric tests at 17 frequencies ranging from 125 Hz to 16 kHz. To analyze effects of age the children were assessed in age groups of 6 to 9, 9 to 12, and 13 to 16 years of age.
Children in China and Germany have the poorest hearing sensitivity at low frequencies (below 1 kHz) and the best sensitivity at the extended high frequencies above 8 kHz. The mean deviations (both ears) from the standard thresholds for adults 18 to 25 years of age, averaged over all frequencies, are 6.7 dB for Chinese and 7.1 dB for German children in the youngest age groups. In the Chinese age group of 9- to 12-year olds the averaged threshold is 4.5 dB and for the same German age group 3.6 dB. For the Chinese age group of 13- to 16-year olds the averaged threshold is 3.3 dB. The improvements of the older German age group compared with the younger are significant at p < 0.05 and are nearly twice as high compared with the comparable Chinese age groups.
Age-dependent improvements of hearing ability are evident in children and should be considered in evaluating audiometric test results. Audiometric tests in the extended high-frequency range could be used as an early warning system for future degeneration of hearing ability.