Effect of audiometric test room noise on monaural and binaural thresholds

Abstract

This study determined if the maximum permissible ambient noise levels (MPANLs) for audiometry specified in the revision of ANSI S3.1-199x provided the same amount of threshold shift for monaural and binaural listening. Sound-field monaural and binaural warble-tone thresholds (125–8000 Hz) were obtained on 24 normal-hearing subjects in quiet (ambient) and in two background noise conditions. One noise condition approximated the ANSI S3.1-199x ears not covered MPANLs (ANSI noise). The other noise condition was 20 dB higher than the ANSI MPANLs (ANSI noise + 20). Monaural thresholds were about 2 dB higher than binaural thresholds in quiet and in each noise condition. The difference between the monaural minus the binaural threshold shifts in each noise condition (ANSI noise + 20 minus ambient; ANSI noise minus ambient) averaged over frequency was typically less than 1 dB. Thus the MPANLs in the revision of ANSI S3.1-199x are appropriate for both monaural and binaural testing.