This part of ISO 389 specifies reference levels for narrow-band masking noise presented by air con-duction 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 appro-priate acoustic coupler, ear simulator or artificial ear.
Data are given for noise bandwidths of one-third and one-half octaves.
NOTE 1 Some notes on the derivation of the reference levels are given in annex A.
BS EN ISO 389-4:1999 history
1970BS EN ISO 389-4:2004 Acoustics — Reference zero for the calibration ofaudiometric equipment — Part 8 : Reference equivalent threshold sound pressure levels for pure tones and circumaural earphones
1995BS EN ISO 389-4:1999 Acoustics - Reference zero for the calibration of audiometric equipment - Reference levels for narrow-band masking noise
1995BS EN ISO 389-4:1995 Acoustics - Reference zero for the calibration of audiometric equipment - Reference levels for narrow-band masking noise