APPLICABILITY OF THE L(EQ) AS A DAMAGE-RISK CRITERION - AN ANIMAL-EXPERIMENT

Within the European communities, the L(eq8h) is used as a damage-risk criterion (DRC) for hearing protection. The use of such a DRC supposes that sound exposures with equal energy imply equal risk for noise-ind uced hearing loss (NIHL). The aim of the present study, carried out wi th guinea pigs, was to test the applicability of the L(eq8h) for estim ating the hazard of different noises having the same spectrum and acou stic energy. Therefore, only the temporal structure of noises was a va riable (continuous, intermittent, or impulsive) and each noise had a L (eq8h) Of 92 dB. The results indicate the L(eq8h) is not an accurate D RC. It overestimates the NIHL for intermittent and short-continuous no ises, whereas it seems to be useful for moderate-intensity noises (95 dB) and for the impulse noise (101 dB). Furthermore, the data point ou t the notion of ''critical intensity'' which seems to play a determini ng role in the transition between metabolic and mechanical mechanisms involved in the acoustic trauma. Since the critical intensity and the existence of two mechanisms are parameters that L(eq8h) cannot take in to consideration, recommendations on the safety program of hearing los s the prevention are discussed. (C) 1996 Acoustical Society of America .