Audiometria ad alta frequenza ed esposizione lavorativa ad ultrasuoni: risultati preliminari

Abstract The aim was to investigate the hearing thresholds in the conventional frequencies (0.25-8 kHz) as well as in the high frequency range (9-18 kHz) and the presence of subjective sympthoms in a group of 14 workers exposed to ultrasound in a glasses manufactory. In order to get reference values, 14 non exposed subjects were tested. Ultrasound emitted by industrial ultrasonic cleaning baths exceeded twice the ACGIH TLV-C for frequencies 20 and 25 kHz. The exposed subjects had significantly higher hearing thresholds than non-exposed subjects at frequencies at or above 10 kHz, the loss being greatest (more than 15 dB) at 12, 13 e 14 kHz. These hearing losses were already evident in subjects with exposure of less than 10 years and increased with years of exposure and advancing age. Subjective sympthoms such as headache, asthenia and vertigo were more frequently reported by the exposed than by the non exposed subjects, even if the differences were not statistically significant.