An Application of the Articulation Index to Hearing Aid Fitting
The application of the articulation index (Al) model to the fitting of linear amplification was evaluated for 12 subjects with sensorineural hearing loss. Comparisons were made of amplification characteristics specified by the NAL (Byrne & Dillon, 1986) and POGO (McCandless & Lyregaard, 1983) prescriptions, as well as a procedure that attempted to maximize the Al (AlMax). For all subjects, the relationship between percent-correct scores on a nonsense syllable test and Als was monotonic for the two prescriptions, indicating that the Al was effective for comparing conditions typical of those recommended clinically. However, subjects having sloping high-frequency hearing losses demonstrated nonmonotonicity due to poor performance in the AlMax condition. For these subjects, the AlMax condition required much more gain at high than at low frequencies, circumstances that Skinner (1980) warned will cause less-than-optimal performance for individuals having sloping high-frequency hearing loss.