Henning E. VonGierke
Armstrong Labs., 2610 Seventh St., Wright--Patterson AFB, OH 45433-7901
A theoretical and experimental study with this title was undertaken in the 1952--1953 period and published in the Benox Report [``An Exploratory Study of the Biological Effects of Noise,'' Univ. of Chicago (1 Dec. 1953) also Am. Indust. Hygiene Assoc. Q. 15(1) (March 1954)] to support protection from increasing noise levels in aviation and industry. The factors explored, quantified, and analyzed by means of an analog circuit of the head-ear-protector system appear to be still the limiting factors in light of subsequent, more detailed investigations. This historical review will also mention later experiments in our laboratory on the bone conduction threshold in a free sound field (1959), on the development of extra large and extra small sizes for the V-51R earplug (1956), on improving ear protector effectiveness beyond the passive limits by static pressure changes [U.S. patent 2,719,523 (4 Oct. 1955)], and early experiments on active noise cancellation.