@article{ref1,
title="Impulse noise and risk criteria",
journal="Noise and health",
year="2003",
author="Starck, J. and Toppila, Esko and Pyykko, I.",
volume="5",
number="20",
pages="63-73",
abstract="Impulse noise causes evidently more severe hearing  loss than steady state noise. The additional effect of occupational impulse  noise on hearing has been shown to be from 5 to 12 dB at 4 kHz audiometric  frequency. Reported cases for compensated for hearing loss are prevalent in  occupations where noise is impulsive. For impulse noise two measurement methods  have been proposed: the peak level method and energy evaluation method. The  applicability of the peak level method is difficult as even the recurrent  impulses have different time and frequency characteristics. Various national  risk criteria differ from international risk criteria. In France the maximum  A-weighted peak level is 135 dB, and in the United Kingdom the C-weighted peak  sound pressure is limited to 200 Pa (140 dB). This criterion of unweighted 200  Pa (140 dB) is used in European Union (EU) directive 86/188 and ISO 1999-1990  regardless of the number of impulses. The American Conference of Governmental  Industrial Hygienists (ACGIH) has recommended that no exposure in excess of a  C-weighted peak sound pressure level of 140 dB should be permitted. At work  places these norms do not cause any practical consequences since the impulses  seldom exceed 140 dB peak level. In several occupations the impulses are so  rapid that they contribute only a minimal amount to the energy content of noise.  These impulses can damage the inner ear even though they cause reduced awareness  of the hazard of noise. Based to the present knowledge it is evident that there  is the inadequacy of the equal energy principle in modelling the risk for  hearing loss. The hearing protectors attenuate industrial impulse noise  effectively due to the high frequency contents of impulses. Directive regarding  the exposure of workers to the risks arising from noise requires that in risk  assessment attention should be paid also to impulsive noise. So far there is no  valid method to combine steady state and impulse noise. A statistical method for  the measurements of industrial impulse noise is needed to get a preferably  single number for risk assessment. There is an urgent task to develop risk  assessment method and risk criteria for impulsive noise to meet the requirements  of the upcoming European Union noise directive.",
language="",
issn="1463-1741",
doi="",
url="http://dx.doi.org/"
}