Home Email this page Print this page Bookmark this page Decrease font size Default font size Increase font size
Noise & Health  
 Next article
 Previous article
Table of Contents

Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Citation Manager
Access Statistics
Reader Comments
Email Alert *
Add to My List *
 * Requires registration (Free)

 Article Access Statistics
    PDF Downloaded114    
    Comments [Add]    
    Cited by others 1    

Recommend this journal


Year : 2005  |  Volume : 7  |  Issue : 26  |  Page : 47--53

Effects of coldness on the protective performance of earmuffs

Finnish Institute of Occupational Health, Helsinki, Finland

Correspondence Address:
J Starck
Director of the Department of Physics, Finnish Institute of Occupational Health, Topeliuksenkatu 41 a A 00250 Helsinki
Login to access the Email id

Source of Support: None, Conflict of Interest: None

PMID: 16053605

Rights and PermissionsRights and Permissions

The type test of hearing protectors (HPD) for certification purposes will be conducted in laboratory at room temperature. Optionally, the mechanical durability of HPDs will be tested in cold environment by a drop test. The purpose of this study was to find out the relevance of the drop test, the change of performance in HPD protection, and finally to estimate the possible change of protection efficiency against noise in cold environment. In total, 22 HPDs were selected to the measurements: 18 earmuffs, and 4 earmuffs attached to an industrial helmet. Attenuation of each earmuff cup was measured by applying insertion loss method for the test subjects in cold. The change of attenuation and temperature of cushion ring was followed up to nine minutes using 30-second intervals for sampling. Three HPDs were damaged in the test. The replaceable cushion was broken in two earmuffs and in one helmet-mounted HPD. The replaceable parts were replaced, and the HPD with attachment failure was removed from insertion loss measurement. In nine HPDs the relative change was less than 3 dB, and was at worst 10 dB. This change was typically at low frequencies, 125 Hz at the beginning when cooled HPDs were placed. In various HPDs the time to get the attenuation levelled varied from 1.5 minutes to 8 minutes. The recovery was dependent on the temperature of the cushion ring. In all cases the temperature of the full attenuation was achieved when the cushion ring reached 7oC. This temporary decrease in attenuation will have a minor effect to the protection efficiency, when the HPD is used full time during the whole exposure duration. A typical group of forest workers will have their exposure interrupted. The chain saws have to refuel, and the chain needs to be sharpened about every 40 minutes. During 6 hour daily operational time there will be about 9 - 10 minute break, long enough to cool the cushion ring back to below zero at -10oC, if the helmet mounted earmuffs are placed in stand-by position. In the worst case this will cause 1.6 dB increase in daily exposure level to noise.


Print this article     Email this article