Military Audiology Short Course

MASC 2005 Abstracts

Auditory Hazard Assessment Algorithm for Humans

Richard G. Price, Ph.D.

Assessing the hazard from intense sounds remains a technically perplexing problem. It is a major issue for the weapons designers, the user and the medical community. Over the years, many have worked to create models of various parts of the ear. But for the purpose of predicting hazard, five things have been lacking:

  1. algorithms connecting a directional sound field with the ear,
  2. a nonlinear model for the stapes suspension,
  3. a model that accounts for middle ear muscle contractions,
  4. a hazard model at the level of the cochlea and
  5. the integrative “glue” that begins with pressure in the free field and ends with hazard calculated within the cochlea.

The process of developing the integrated model has taken place at the US Army Research Laboratory over a number of years and has involved iterative processes in which algorithms or values have been arrived at and tested by comparison with data from noise exposure experiments. The model has been deliberately formulated in such a way that it is possible to relate its elements to the physiology of the ear. It has been peer reviewed and validated with data from over 70 experiments with human ears. Far more accurate than existing methods as well as theoretically based, it is being proposed as an alternative to the MIL Standard 1474 (Department of Defense Design Criteria Standard: Noise Limits), the current method of noise hazard determination. The presentation will provide an overview of the model and its application.