BS EN ISO 389-4:1994 : Implementation of ISO 389-4:1994 Acoustics — Reference zero for the calibration of audiometric equipment — Part 4. Reference levels for narrow-band masking noise
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This part of ISO 389 specifies reference levels for 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 equivalent threshold sound pressure levels for the corresponding pure-tone frequencies as specified in ISO 389:1991 or ISO 389-2, respectively, when the masking earphone is placed on the appropriate acoustic coupler, ear simulator or artificial ear.
BS EN ISO 389-4:1994 : Implementation of ISO 389-4:1994 Acoustics — Reference zero for the calibration of audiometric equipment — Part 4. Reference levels for narrow-band masking noise