Proceedings of 20 th International Congress on Acoustics, ICA 2010 23-27 August 2010, Sydney, Australia ICA 2010 1 The assessment of auditory damage risk in particularly noisy environments F. Gugliermetti, C. Aureli, A.C. Violante Department of Fisica Tecnica – University of Rome “Sapienza”, Via Eudossiana n. 18, 00184 Rome, Italy PACS: 43.50 QP Effects of noise on man and society. ABSTRACT The most negative effects caused by noise exposure related to the hearing system are well known and may produce professional or even permanent deafness. Since these effects have very important influence on worker’s health and well-being, it is necessary to evaluate the hearing loss caused by occupational exposure to noise in order to propose preventive solutions. A large number of compensation claims are submitted each year in Italy for the occupational disease “hypoacusis”. The criticalities for assessing the risk of auditory damage is related to the fact that a scientifically accepted relation between hearing loss and noise frequency still not exist for the Italian population. Besides, at today there is not crite- rion of damage accepted by the scientific community for several different work field. In this work, we present a me- thodological approach for calculating the provisional risk of auditory damage for the airport ramp’s operators. The calculation method is based upon on the definitions and the Annexes of the ISO 1999/90, the table of biological dam- age to the hearing loss of D.M. 12/07/2000 (Italian Ministerial Decree) and the four damage criteria defined by S. Ca- sini (Italian National Institute for Insurance against Accidents at Work). The approach considers the hearing loss as caused not only by the occupational exposure to noise, but also by biologic ageing. The risk matrices have been eva- luated basing on the numerical results obtained by simulations performed with the software Rumours. One matrix for each criterion of damage has been developed. INTRODUCTION Exposure to intense noise, even for a short period of time, can cause irreversible hearing loss. The same type of hearing damage can be caused by prolonged exposure to noise in moderately noisy environments. The harmful effects of noise on humans are divided into spe- cific auditory effects that interest the hearing apparatus [1], and extra-auditory effects, that can cause different disturbs [2], like stress, loss attention, increase of blood pressure,and many others. The cardiovascular system would appear to be the one that is most influenced by noise, directly as well as indirectly. Analysis of available literature shows that, with an intensity generally higher than 85 dB(A), there is an increase in cardiac frequency, blood pressure, peripheral vascular resistance and the concentration of noradrenaline, and often of adrenaline, present in the blood and urine, when an intensi- ty higher than 85 dB(A) occurs. The damage that can be produced by continued exposure professional to noise is called “hypoacusis”. Hypoacusis, that is the impairment and eventual loss of hear- ing, is the best known and most studied type of noise induced damage. However, noise also interacts in a very complex way with other bodily organs and systems (cardiovascular system, endocrinous system and central nervous system among oth- ers) through the activation or repression of central or peri- pheral neuroregulatory systems [3]. Noise also has a conceal- ing effect that hampers verbal communications and the per- ception of acoustic safety signals (with a consequent increase of the probability of occupational accidents). It favours the onset of mental fatigue, reduces the efficiency of professional performance, causes learning disorders and interference with sleep and rest [4]. In Italy, noise induced hypoacusis is the most frequently reported of all occupational diseases. INAIL (Italian National Institute for Insurance against Accidents at Work) data shows that noise induced hypoacusis and deafness constitute ap- proximately half of all occupational diseases. In terms of hearing related effects, noise acts on the ear pri- marily through acoustic energy. Exposure to noise at high intensities and for long periods causes a series of alterations to the neurosensorial structures of the inner ear. The organ of Corti, located inside the cochlea, is the area most prone to noise-induced damage. Exposure to noise can also cause irreversible damages if it is prolonged over time. Such irreversible lesions demonstrate with a permanent rise of the hearing threshold. Noise damage typically emerges as bilateral perceptive hypoacusis [5]. Higher intensity noise, not lower than 120-130 dB, also af- fects the vestibule portion of the inner ear, with dizziness, nausea and balance disorders, that are usually reversible, disappeaning with the interruption of the acoustic stimulus. A healthy ear with complete hearing ability has a threshold sound level of zero, which indicates the minimum intensity of perceivable sound. Hearing loss, or hypoacusis, measured in decibels, expresses the difference between the minimum sound level that the ear is able to perceive and zero, conven- tionally considered as standard. In a subject with normal