Abstract:
The concepts of the modified power law (MPL) and the continuation hypothesis (CH) are outlined and then empirical evidence is presented which suggests that the MPL, not the CH, is the appropriate method for predicting noise-induced permanent threshold shift (NIPTS) in persons with sensorineural hearing impairment. The ISO1999 rule for combining presbyacusis and NIPTS is explained and empirical evidence is presented which indicates that the ISO1999 rule, not the MPL, is the appropriate method for combining NIPTS and presbyacusis. These findings are then used to predict the progression of hearing loss in a person whose thresholds are affected both by aging and by two separate periods of occupational noise exposure. The results are compared with those obtained using the CH instead of the MPL to predict the progression of NIPTS and with those obtained using the MPL instead of the ISO1999 rule to combine presbyacusis and NIPTS.