ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

3pNS2. The effects of reverberant blast waves on hearing: Energy and spectral considerations.

William A. Ahroon

Sheau-Fang Lei

Roger P. Hamernik

Auditory Res. Lab., State Univ. of New York, Plattsburgh, NY 12901

Chinchillas were exposed to 1, 10, or 100 reverberant impulses at 150, 155, or 160 dB peak SPL. The impulses were generated by one of two different shock tubes each producing blast waves having a different spectral composition; one emphasizing low frequencies (<0.5 kHz), the other mid-frequencies (2--4 kHz). Impulses were presented at the rate of 1/s. This parametric paradigm yielded 18 exposure conditions; 15 animals/condition. Hearing thresholds were measured using auditory evoked potentials and the sensory epithelium was evaluated with the surface preparation. In general, trauma increased as the total energy of the exposure, determined by the peak SPL and number of presentations, increased. The dependent variables (permanent threshold shift and sensory cell loss) varied in an orderly fashion across frequency as the peak and number of presentations was increased for both blast wave sources. There were, however, consistent differences between the effects of the low- and high-frequency energy ``content'' blast waves. Correlations between the dependent variables and the energy of exposure were highest for P- or A-weighted energies [Patterson et al., 2860--2869 (1993)]. [Work supported by U.S. Army Medical Research and Development Command.]