Abstract
It is suggested that the audiometers be calibrated and hearing thresholds be recorded in terms of actual sound pressure levels (zero decibels = 0.0002 microbars). This simple physical basis avoids the inevitable uncertainties of a calibration based on a physiologic normal. It is felt that the use of a physical unit is more meaningful and more stable than the statistical value from studies of the hearing thresholds of healthy young adults which form the basis of the zero reference levels of the ASA 1951 standard as well as the 1963 recommendations of the International Organization for Standardization (ISO). The same unit would then serve as the basis for expression of hearing thresholds and of noise measurements.