[Suitability of the middle acoustic evoked potential P35 for frequency-specific measurements]

Objective audiograms (500, 1000 and 3000 Hz) have been produced by the help of the middle auditory evoked potential P35 (Fig. 3). The adjustment of the computer audiometer was optimized in such a manner that the reproducible measurement of the potential P35 was feasible even near the hearing threshold. In particular, the setting of the low and high pass filter, the shape of the auditory stimulus and the interstimulus interval have been varied. The latency of the potential was found to increase in good correlation with decreasing intensity of the tone burst. Reference curves of the sound intensity - latency dependence were derived from the examination of 13 subjects with normal hearing, aged 18 to 59 years (Fig. 4). The theoretically expected frequency specificity of the method was proved by the examination of patients suffering from a wide variety of selective hearing losses. In addition, statements on the recruitment are found to be feasible. Reports of four selected cases are presented: a labyrinthine hearing loss (Fig. 5), two acute hearing losses (Figs. 6 and 7) and a neural hearing loss (Fig. 8).