SOME general results of the analysis of hearing patterns in a rural Illinois school system have been previously described.1 The present paper is a consideration of certain more exact aspects of the hearing of the same population.
In brief review, the population under consideration in this analysis consisted of all the children in grades 5, 7 and 9 in two Illinois counties, DeWitt and Piatt. These children were tested during the month of March 1949. The total number of the school population, 6,062, was viewed as a rural population by the members of the health unit who were responsible for this analysis of the hearing acuity of this population. Children in the grades indicated were tested with a pure frequency sweep of 15 decibels intensity at seven frequencies (256 to 11,584). All children who failed to pass this sweep test were given an individual pure frequency audiometric test on