Threshold for Normal Hearing

Abstract

The Walter Reed General Hospital, in cooperation with the National Bureau of Standards, has undertaken an intensive investigation to establish an accurate and realistic threshold for normal hearing. Stringent criteria were observed in selecting subjects. By careful instrumentation it was possible to measure the sound-pressure levels at the entrance of the external acoustic canal, as well as the voltages across the terminals of the earphones used.

The data obtained by the Walter Reed General Hospital has been compared to the data obtained by other investigators. There exists a close agreement between the British and the Walter Reed data. It may safely be assumed, therefore, that the study rules out the possibility of locality, selection of subjects, and testing conditions as an explanation of differences in normal thresholds. Although several discrepancies are apparent when the Walter Reed data is compared with investigators other than the British, the general trend of the data appears to indicate that the present American Standard for normal threshold of hearing is incorrect. It follows logically that steps should be initiated to correct the situation after first evaluating the implications that such a change would have.