Quantifying psychoacoustic tuning curves for clinical use.

Psychoacoustic tuning curves (PTCs) were obtained in a number of normal-hearing and hearing-impaired subjects using a simultaneous tone-on-tone masking technique. PTCs at three different centre frequencies (500, 1,000 and 2,000 Hz) were studied. In order to estimate the degree of frequency selectivity of the inner ear, an algorithm for quantification of PTCs was constructed. The method of linear regression was used to calculate the slopes of the linearized curves. Three different parameters of the curve, the low and high frequency slope and the height of the curve, were calculated using computer programs which allowed automatic evaluation of the data. The values of these parameters concerning normal and hearing-impaired subjects are presented in terms of scores and percentages of normal values. The algorithm for quantification of PTCs presented in this paper may in clinical work serve as a method of evaluating auditory frequency selectivity, particularly for very abnormal PTCs.