Figure 1A-C. A: Mean pure tone thresholds in dB HL exceeding the screening level 20 dB HL for the frequencies 0.5 kHz, 4 kHz and 6 kHz, left ear, for the screening audiograms at age 18 for each of the age groups. B-E: epidemiological information about four contagious diseases in Sweden for the years 1952-1980. Annually reported cases of infl uenza (B) varied from 276,000 (1957) to 5,435 (1980). Reported cases of pertussis (C) varied from 20,000 (1957) to 762 (1972). The annual number of reported cases of measles (D) varied from 12,200 (1955) to 1,786 (1980). Regarding rubella, two data bases were used: reported cases of military servicemen within the Armed Forces (1952-1973) and in the general population (1969-1980). In the general population the reported numbers varied from 13,013 (1974) to 2,509 (1977).