Impulse noise hazard: From theoretical understanding to engineering solutions

We have several methods for rating hazard from gunfire impulses worldwide; but none works well. The problem is acute because maintaining good hearing is critical for military performance (lower levels of exposure desirable) just when lightweight weapons with greater power are needed (higher energies typically present). The problem with respect to rating hazard is that existing criteria are not theoretically based and unrelated to critical properties of the ear. In response to this need, the US Army Research Laboratory (ARL) has created and validated the auditory hazard assessment algorithm for the human (AHAAH). AHAAH is an electro-acoustic analog of the ear, conformal with its structure, and accounts for its spectral tuning, the change of loss mechanism with level, middle ear muscle effects, displacement limiting by the middle ear, and its operation in the time domain. By using the AHAAH model and the movie it creates of the action of sounds in the inner ear, we are able rate hazard accurately and explain critical data where other methods have failed. Through its use we can demonstrate development of engineering insights that resolve or ameliorate problems. The AHAAH model software is ready for use and supporting material can be downloaded from the ARL website