[Changes in the auditory threshold of workers exposed to the combined action of noise and local vibrations].

Study is performed on the effect of noise and local vibrations during a combined effect and independently on the auditory threshold for 4 kHz. The audiometric data of 1242 workers from the textile industry, coal- and ore production are analysed. On the basis of precise assessment of the noise level and occupational exposure to noise and local vibrations are formed 4 groups: exposed to independent noise effect with intensity 90 and 100 db (spinners and dressmakers); exposed to combined effect of noise (91 and 103 db) and local vibrations, surpassing the maximum admissible norms respectively 2.5 and 3.5 times (miners of coal- and ore production). In view of the occupational exposure and standardization concerning age and length of service the audiograms of 248 persons are examined. The following is established: different rate of increase of the auditory threshold for 4 kHz depending on the intensity of the factors noise and local vibrations in conditions of independent and combined effect: positive correlation with the length of service in the changes of the auditory sensoriness; dynamics in the increase of the auditory threshold for 4 KHz.