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.
- AIBS Peer-Review of Impulse Noise Injury Models (2010)
- Executive Summary of the Development and Validation of AHAAH
- MIL-STD 1474D Method of Hazard Prediction
- AIBS Peer-Review of AHAAH (2001)
- Clarification of the AIBS Peer-Review of AHAAH (2001)
- Click here for the Web application version of the AHAAH model.
- The Web application is not for use with Military Standard 1474E; download version 2.1 for MIL-STD-1474E applications
- 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
- An Examination of and Response to "Auditory Standard Issues" by Dr. James Stuhmiller
- Stability of the Auditory Hazard Assessment Algorithm for Humans (AHAAH)Model by G. Richard Price and Joel T. Kalb (2013)
- AHAAH Hearing Protection Module (Version 2.1) with Level-Dependent Parameters for the Double-ended Combat Arms Earplug by Joel T. Kalb and Paul D. Fedele (2014)
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 Dataset 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
- A hearing protector model for predicting impulsive noise hazard (Kalb, NOISE-CON 2010)
- Mathematical Model of the Ear's Response to Weapons Impulses (ARL-RP-0521)
- Level-Dependent Non-Linear Hearing Protector Model in the Auditory Hazard Assessment Algorithm for Humans (ARL-TR-7271)
- Using the Auditory Hazard Assessment Algorithm for Humans (AHAAH) With Hearing Protection Software, Release MIL-STD-1474E (ARL-TR-6748)
- 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)
- Using the Auditory Hazard Assessment Algorithm for Humans Software Beta Release W93e (ARL-TR-4987)
- An Analysis of the Blast Overpressure Study Data Comparing Three Exposure Criteria. NIOSH Report No. EPHB 309-05h (Murphy, Khan, and Shaw)
- Critique of 'An Analysis of the Blast Overpressure Study Data Comparing Three Exposure Criteria, by Murphy, Khan, and Shaw. (ARL-CR-657)