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margin-left:auto; margin-right:auto"> <col width="25%" /> <col width="25%" /> <col width="25%" /> <col width="25%" /> <tr> <td class="navigation"><a href="definitionNoise.php" class="navigation">Noise</a></td> <td class="navigation"><a href="ear.php" class="navigation">The ear</a></td> <td class="navigation"><a href="effectsNoiseEar.php" class="navigation">Noise and us</a></td> <td class="navigation"><a href="prevention.php" class="navigation">Prevention</a></td> </tr> </table> </noscript>   <table width="775" height="441" border="0" cellpadding="0" cellspacing="0" style="margin-left:auto; margin-right:auto"> <col width="195" /> <col width="*" /> <tr> <td class="position" colspan="2"> <a href="definitionNoise.php" class="yellow">Files</a> > <a href="#" class="yellow">Noise and us</a> > <a href="#" class="yellow">The effects of noise on the ear</a></td> </tr> <tr> <td valign="top"><img src="../images/img_doseffets.jpg" width="195" height="249" alt="Le bruit et nous" /> <table width="100%" cellpadding="3" cellspacing="0"> <tr> <td><a href="effectsNoiseEar.php" class="menu"style="color:#1761AB;font-weight:bold;">> Effects of noise on the ear</a></td> </tr> <tr> <td><a href="effectsNoiseBody.php" class="menu">> Effects of noise on the body</a></td> </tr> </table> </td> <td valign="top" class="bordure"><h1 class="titrePage">The effects of noise on the ear</h1> <p>The constant acoustic load in our environment may result in hearing deficiencies from a very early age. A hearing disorder may already occur at a constant noise level of 85 dB, which corresponds to the noise of a street with heavy traffic or the noise in a workshop.</p> <ul> <li><a href="effectsNoiseEar.php?txt=1" class="bleu">Why do we find it more difficult to hear?</a></li> <li><a href="effectsNoiseEar.php?txt=2" class="bleu">Auditory fatigue</a></li> <li>The types of deafness</li> <p><span class="bold">Traumatic deafness: </span><br /> Brief but very violent exposure may cause considerable damage. Some sudden noises may result in a genuine hearing injury and lead to permanent deafness (an explosion for example). </p> <p><span class="bold">Gradual deafness: </span><br /> Prolonged exposure in an acoustic environment exceeding 85 dB may cause total or partial deafness.</p> <p>In France, more than two million people are reported to be subject to prolonged exposure at their workplace. Some of them are reported to suffer from irreversible deafness. </p> <p><span class="bold">Occupational deafness</span> is assessed according to well-defined medical, occupational and administrative criteria, which are stipulated in table no. 42 of occupational diseases. </p> <p><span class="bold">Medical monitoring </span><br /> Only monitoring of hearing by the occupational physician makes it possible to detect a person’s sensitivity to noise and make assessments of hearing losses. During the examination which allows assessment of hearing level, an audiogram is performed under specific conditions using an audiometer.</p> <p class="centre"><img src="../images/dossiers/effetsDuBruit.jpg" width="400" height="260" alt="Graphique de la perte auditive" /></p> <p><span class="bold">Stage 1:</span><br /> Recovery between periods of exposure to noise is no longer complete. The individuals do not notice their hearing losses, since the frequencies of speech are unaffected. The hearing losses are initially situated in high-pitched frequencies. <br /> Only an audiogram allows detection of this onset of deafness. </p> <p><span class="bold">Stage 2:</span><br /> Gradually, the hearing losses spread to the so-called "vocal" frequencies. The subject no longer clearly hears what is said to him or her. He/she discovers his/her deafness... too late. </p> <p><span class="bold">Stage 3:</span><br /> Deafness is profound and irreversible.<br /> Two characteristics differentiate it from the other types of deafness:</p> <ul> <li>it does not improve, </li> <li>it does not get worse when the nuisance ceases. </li> </ul> </ul></td> </tr> </table>   <div style="width:775px;margin-left:auto; margin-right:auto; text-align:center"><p class="adresse">COTRAL International BP100 14110 CONDE SUR NOIREAU - Tél : +33 (0)2 31 69 36 36 - Fax : +33 (0)2 31 69 36 35</p> <p class="adresse">COTRAL International, Secrétariat commercial Bahnhofstrasse 52 CH-8001 ZÜRICH - Tél : +41 (0)44 214 67 24 - Fax : +41 (0)44 214 65 19</p> <p class="adresse">COTRAL International, Secrétariat commercial 8 Avenue des Arts B-1210 BRUXELLES - Tél : + 32 (0) 2 545 11 52 - Fax : +32 (0) 2 545 11 46</p> <p class="obligation"><a href="../protectionPersonnalData.php" class="cnil">Disclaimer</a></p></div>  <script type="text/javascript"> var gaJsHost = (("https:" == document.location.protocol) ? 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