Audiometric screening was carried out on 3,322 elementary and high school students living in the vicinity of Logan International Airport, Boston, in an effort to determine whether noise from aircraft had any measurable effect on their hearing. Followup examinations and additional data on children failing the screening examination made it possible to classify the hearing losses as conductive, sensorineural, or mixed. The incidence of bilateral sensorineural or mixed hearing loss in the group living directly under flight paths or immediately adjacent to runways was not significantly different from the overall average. In normal subjects, the average sensorineural gap, a newly defined measure of high-tone loss, was not found to be significantly affected by the degree or duration of exposure to aircraft noise.