Auditory Hazard Assessment Algorithm for Humans (AHAAH)

Auditory Hazard Assessment Algorithm for Humans (AHAAH)

Modern weapons and a broad spectrum of industrial machinery produce intense acoustic impulses that can make them unsafe, limit their use, or restrict their design. Recent studies indicate 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.



  • Click here for the Zip (Version 2.0) of the AHAAH model. This version includes Power User Hearing Protector Features. Version 2.0 is not for use with Military Standard 1474E: Design Criteria Standard - Noise Limits.
  • Click here for the ZIP (Version 2.1) of the AHAAH model for use with Military Standard 1474E: Design Criteria Standard - Noise Limits. This version includes default hearing protectors specified in MIL-STD-1474E.

* MIL-STD-1474E: Design Criteria Standard: Noise Limits, dated 15 April 2015, has been published and is available on the ASSIST website.
* An ARL Technical Report entitled: "Using the Auditory Hazard Assessment Algorithm for Humans (AHAAH) with Hearing Protection Software, Release MIL-STD-1474E" has been published.
* AHAAH Version 2.0 has been revised to Version 2.1 to incorporate level-dependent parameters of the double-ended Combat Arms Earplug. See the information paper entitled "AHAAH Hearing Protection Module (Version 2.1) with Level-dependent Parameters for the Double-ended Combat Arms Earplug"
* An ARL Technical Report entitled:"Level-Dependent Non-Linear Hearing Protector Model in the Auditory Hazard Assessment Algorithm for Humans" has been published

Configuration Management Plan

The AHAAH configuration management plan (CMP) has been developed to control and manage AHAAH configuration items. The oversight authority for changes to AHAAH is the AHAAH Configuration Control Board (CCB).

Click here for the AHAAH Configuration Management Plan (Version 1.0.0, dated 21 August 2015)

Response to Technical Issues

Scientific Basis for the Model

Technical Reports

Support for Peer Review


Last Update / Reviewed: September 24, 2015