Challenge of epidemiological research in the developing world: overview.

Listing the eight most important aspects of epidemiological research relevant to hearing loss, this paper reviews some of the difficulties encountered in trying to do such research in the developing world. Various research formats are discussed. This paper concludes with a review of what has been reported in the world's literature about the incidence and prevalence of sensorineural hearing loss in children. The average finding from 34 nations is 1.368 hearing impaired per 1,000.