Nonlinearity in the auditory hazard assessment algorithm for humans

The Auditory Hazard Assessment Algorithm for Humans (AHAAH) is a software application that evaluates hearing damage risk associated with impulsive noise (http://www.arl.army.mil/ahaah). AHAAH applies pressure response dynamics across the external, middle, and inner ear, to bio-mechanically model the ear’s physical response to impulsive sound. Cumulative strain-induced fatigue in the cochlea’s organ of Corti determines the risk of auditory hazard. AHAAH includes nonlinear behavior observed in stapes displacement and associated with the annular ligament in the middle ear. AHAAH’s nonlinear behavior has been validated by Price (2007) based on human test results produced by Johnson (1966, 1993, and 1997). Presented analyses results show that the risk of hearing hazard cannot be predicted solely on the basis of waveform energy (A-weighted or not) or waveform peak pressure, because of the middle ear nonlinearity. The risk of hearing hazard does not necessarily behave monotonically with any summary waveform char...