Studies of Aural Nonlinearity and the Mechanisms of Auditory Fatigue. Part 2. Epidemiologic Methods in Noise-Induced Hearing Loss

Abstract : The past two decades have witnessed a growth in the number of scientists concerned with the distribution of noise induced hearing loss (NIHL) in industrial populations. Studies conducted by these scientists have incorporated some of the epidemiological principles which have evolved for studying other chronic diseases; however, many available methodological and analytical techniques have been overlooked. Behind all of these is one goal - how to obtain appropriate data and what form of analysis is used to get accurate answers to questions with a minimum of expenditure? The general questions are: (1) What rates summarize the frequency of NIHL in a population? How does one obtain and utilize these different rates?; (2) What risk measures are suitable for examining the degree of association between exposure and morbidity for making population predictions or for assessment of individual risk? How do prognostic factors affect this risk?; (3) What are the sampling schemes which can be employed to measure risk? What are the advantages and disadvantages of each? What control groups can be used?; and (4) Can one identify factors contributing to the differences in susceptibility of groups or individuals to NIHL? (kr)