Reducing hearing protector test time with a minimum audible pressure to field transfer function

Abstract

Effective hearing-loss prevention programs should train workers to properly fit hearing protection devices. In order to minimize the training time for protector fitting, unoccluded minimum audible field threshold (MAF) for narrow-band noise could be estimated from the worker’s annual minimum audible pressure (MAP) audiogram. Murphy et al. previously reported a transfer function for 5- and 1-dB audiometry for 75 and 10 subjects, respectively [W. J. Murphy, J. R. Franks, S. L. Hall, and E. F. Krieg, J. Acoust. Soc. Am. 101, 3126 (1997)]. Significant differences at several frequencies between the 1- and 5-dB groups prompted further study of the transfer function. This paper reports MAF and MAP results for 44 subjects tested with both 1- and 5-dB audiometry and 1-dB sound field. Pure-tone thresholds were significantly different, for 1- and 5-dB step sizes. The binaural reference equivalent threshold sound pressure level (RETSPL) sound-field thresholds were compared with the RETSPL thresholds for monaural listening in a sound-field listed in ANSI S3.6-1996, Table 9. The binaural thresholds were found to be significantly higher (p<0.05) than the standard values at all frequencies except 8000 Hz.