The authors evaluate in a group of 25 subjects with normal hearing, starting work involving exposure to noise, the development of distorsion product otoacoustic emissions and transient evoked otoacoustic emissions in time during five consecutive measurements made after six-month intervals. Regression analysis provided evidence of a tendency of declining amplitude of distorsion product emissions in time during unchanging values of the sound audiogram.The authors observed also in the same group deterioration of the reaction of transient otoacoustic emissions intime. The results of the investigation suggest the possibility of early detection of developing hypacusia in workers exposed to the risk of noise by means of otoacoustic emissions.

        Key words: DPOAE, otoacoustic emissions, occupational medicine, TEOAE, examination of hearing.