4pPPb7. Risk assessment for occupational noise induced hearing loss: W. Dixon Ward and the ``Anti-Chicken Little Movement.''

Session: Thursday Afternoon, June 19

Author: William W. Clark
Location: Central Inst. for the Deaf, 818 S. Euclid Ave., St. Louis, MO 63110


One of the hallmarks of W. Dixon Ward's illustrious career was his proclivity to criticize effectively the efforts of his colleagues. Depending upon the topic and the victim, this ability led him to be characterized as an outstanding editor, a thoughtful reviewer, an overzealous critic, or an impediment to consensus. Despite the variety of responses, Dix's critiques shared one characteristic: They were almost always correct. One of his favorite targets was the international standard, ``Acoustics---Determination of occupational noise exposure and estimation of noise-induced hearing impairment'' (ISO 1999, 1990). Throughout the two decades of its development Dix took to task the framers of the standard, challenging the assumptions which underly it. Dix was particularly vexed by ISO's use of the 3-dB exchange rate, the presumption of 0% risk of noise induced hearing loss for those nonoccupationally exposed, and the estimation that normal 18-year-olds have perfect hearing. In this tribute, Dix's criticisms of the ISO standard will be articulated and supported with recent data, and his role as the leader of the ``Anti-Chicken Little Movement'' justified.

ASA 133rd meeting - Penn State, June 1997