RESULTS OF THE WORLD'S FAIR HEARING TESTS 



543 



TABLE 5 

 Percentage of Tests with Hearing Loss Greater than 25 and 45 db. 



gressive condition which may later involve tones of lower frequency. 

 It is striking to note that, of the people taking the hearing test at the 

 World's Fairs, some 6 per cent in the 20-29 year age range showed a 

 hearing loss in excess of 25 db for the 7040 cycle tone. In the oldest 

 age range half of the people showed such a loss. It is likely that an 

 even larger proportion would be found in a random sample of the 

 population, for, as will be discussed in a subsequent section, it is 

 believed that the people taking the test at the Fair represent an 

 economic status that is average or better, and there are indications 

 of a greater prevalence of hearing defects in the lower economic 

 groups. 



The Estimation of Age 



As previously indicated, estimates were relied upon to furnish 

 information on the ages of the visitors taking the hearing test. The 

 attendant making these estimates was changed every hour or so, about 

 fifty being used in the course of a week at the New York Fair. In 

 order to determine the accuracy of the estimates, 267 test blanks of 

 members of Bell Telephone Laboratories families were examined and 

 the real age compared with the estimated age indicated on the blank. 

 In most cases the attendant who made the estimate was not aware 

 that the individual was a member of the Bell System. It was found 

 that 62 per cent of the real ages were within the estimated 10 year 

 age group, while 83 per cent were not more than 3 years outside of the 

 group and 96 per cent were not more than 8 years outside of the group. 

 There was a general tendency to estimate high for young people and 

 low for older people. 



