1. 1) ISO 7029 (Second edition), Acoustics — Statistical distribution of hearing thresholds as a function of age (International Organization for Standardization, Geneva, 2000).
2. 2) D. W. Robinson and G. J. Sutton, A comparative analysis of data on the relation of pure-tone audiometric thresholds to age, NPL Acoustics Report AC 84 (National Physical Laboratory, Teddington, 1978).
3. 3) M. S. Shipton, Tables relating pure-tone audiometric threshold to age, NPL Acoustics Report AC 94 (National Physical Laboratory, Teddington, 1979).
4. Pure-tone hearing levels according to age.