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BELL SYSTEM TECHNICAL JOURNAL 



TABLE 7 

 Difference in Mean Hearing Loss at New York and San Francisco 



differences in hearing acuity. Table 7 gives the difference in mean 

 hearing loss between corresponding age groups at New York and San 

 Francisco for the age groups below 50. A positive difference indicates 

 greater hearing loss at San Francisco. 



At the three lower frequencies, the differences are insignificant. 

 The differences at the higher frequencies are not large enough to be 

 conclusive evidence of a sectional difference in hearing, but it seems 

 quite probable that the men taking the test at San Francisco were, on 

 the average, some three decibels less acute than those at New York 

 for the frequencies 3520 and 7040. No important differences in 

 standard deviation or general form of the distribution of hearing loss 

 were noted in comparing the two Fairs. 



For approximately a week at each Fair a question was printed on 

 each hearing test blank asking whether the visitor lived (a) in the city 

 where the Fair was held, {h) within commuting distance, or (c) beyond 

 commuting distance. From the replies to these questions it was 

 found that roughly one-quarter of the visitors at each Fair lived in 

 the city, and another quarter within commuting distance. The 

 remaining one-half were probably well scattered. The test results 

 were analyzed in relation to place of residence. Most of the differ- 

 ences in mean hearing loss were so small that they could easily be 

 attributed to sampling variations. Only one of the comparisons 

 among the various groups showed differences sufficiently large and 

 consistent to be significant. Women from New York City had greater 

 hearing loss at all frequencies than women from the commuting area 

 or beyond, as shown in Table 8. The groups compared number 600 

 and 1400 respectively. The differences did not show any trend with 



