Assessment of Impulse Noise regarding Harmfulness to Hearing

For prevention or for compensation cases, a simple assessment of intensive impulse noise is needed. In order to choose the most appropriate frequency weighting, the transfer function from the free sound field (where we measure) to the inner ear (where damage occurs) must be taken into account. Regarding the most appropriate time constant, the reaction of the inner ear is the reference, and many results indicate that it is not the peak level (rise time 50 microseconds), but rather the short-term sound energy that is correlated with permanent hearing damage. In Switzerland, a sound exposure level LE of 120/125 dB(A) is used as a criterion for damage risk since many years. For very high sound levels (> 170 dB, e.g. heavy weapons), AHAAH should be used which is able to simulate the nonlinear behavior of the hearing system.