Audiometric zero for air conduction. A verification and critique of international standards

The international standard of audiometric zero for normal hearing by air conduction was originally given only for laboratory reference earphones. Subsequently, it has been extended to cover earphones in general audiometric use, and in other ways. A new determination is described in which these derived standards are tested by comparison with the measured thresholds of hearing of 108 subjects in the age range 18-30 years. Particular attention is paid to the otological classification of the subjects and its relation to the description of otological normality in the ISO standards. Suggestions for adjustment of the standards at certain frequencies are made.