[Acoustic evoked potentials in patients with vocal problems in relation to their hearing in wide frequency range]

The function of different compartments of the acoustic analyser was assessed by the findings at tonal audiometry in standard and extended range of frequencies (10, 12, 14 and 16 kHz) as well as by characteristics of acoustic evoked potentials. A total of 62 patients with chronic vocal dysfunction (CVD) and 20 subjects with normal hearing and voice were examined. CVD patients were found to have: normal hearing both in standard and extended range of frequencies (25.8%); normal hearing in standard but defective one in extended range of frequencies (51.6%); defective hearing sensitivity to tones both in standard (4, 6 and 8 kHz) and extended frequency range (22.58%). CVD patients with abnormal hearing in the extended frequency range exhibited affection of the brain stem and cortical compartments of the acoustic analyser. Acoustic evoked potentials were especially abnormal in patients with high hearing thresholds (17.4 +/- 1.6; 25.8 +/- 1.9, 29.7 +/- 2.1 dB) in standard frequency range (4, 6 and 8 kHz), respectively. In such patients the disease ran a protracted course with frequent relapses. These findings can help in making decision on the treatment policy, occupational fitness expertise and selection of patients with vocal professions.