Prescriptive hearing aid fitting by parameter adjustment and selection

We describe the rationale for the development of a psychophysical procedure that allows individual listeners to adjust the frequency-gain characteristic of a programmable hearing aid on a unidimensional scale, based on a target-gain reference value. The listener's task is to adjust the frequency response and select the parametric value judged to optimize the intelligibility or quality of speech. Originally described as the Sliding Scale, the procedure has been modified for use in reliability and validity studies of hearing aid fitting at Michigan State University. The modified approach is referred to as the Parameter Adjustment and Selection (PAS) procedure. Primary immediate goals for the procedure are ease of use, high reliability, and rapid clinical administration. The procedure, which may offer potential advantages over a paired-comparison approach, appears to be generally applicable to the fitting of digitally programmable hearing aids.