Auditory Hazard Assessment Algorithm for Humans (AHAAH)

Modern weapons and a broad spectrum of industrial machinery produce intense acoustic impulses which, limit their use or restrict their design. Recent studies indicated that all current noise exposure standards and design guidelines for impulse generating weapons are seriously in error. To overcome these limitations, ARL's Human Research and Engineering Directorate (HRED) developed a mathematical model of the human auditory system that predicts the hazard from any free-field pressure and provides a visual display of the damage process as it is occurring. The model is a powerful design tool that shows the specific parts of the waveform that need to be addressed in machinery and weapon design. This unique model is the only method of assessing noise hazard for the entire range of impulses that are relevant to the Army. The model has the potential to serve as an international design standard for weapons and to provide damage or risk criteria for intense impulses of industrial origin.

Scientific Basis for the Model

• Weapon noise exposure of the human ear analyzed with the AHAAH model
• Impulse Noise and the Cat Cochlea
• The uniqueness of the Albuquerque data set and "Evaluation of impulse noise criteria using human volunteer data" (J. Acoust. Soc. Am 110, 1967-1975(2001)) by Chan et al.
• Functional Description of the Model
• Validation of AHAAH
• A calculational procedure for incorporating hearing protector variability in health hazard assessments with the AHAAH model
• Auditory Hazard Units as an Index of Risk from Intense Sounds

Technical Reports  

• Evaluation of an auditory hazard model using data from human volunteer studies, USARL Report No. 2005-01 (2004)
• Critical analysis and comment on Patterson and Ahroon (2004) "Evaluation of an auditory hazard model using data from human volunteer studies" USAARL Report No. 2005-01
• Current Status of Rating Hazard from Intense Sounds and The Need for an Update to MIL-STD-1474(D)