scope:

This International Standard specifies reference levels for the calibration of narrow-band masking noise presented by air conduction from an earphone in pure tone audiometry. The data are given in terms of levels to be added to the reference equivalant threshold sound levels for the cooresponding pure-tone frequencies when the masking earphone is placed on the appropriate acoustic coupler or artificial ear. Data are given for noise bandwidths of one-third and one-half octaves. Some notes on the derivaton of the reference levels are given in the annex.