562 BELL SYSTEM TECHNICAL JOURNAL 



boys than in girls. The results of physical examinations of school 

 children conducted by public health officers and doctors in different 

 parts of the country indicate that such is the case. In all but one 

 of seven surveys,^^ involving more than 18,000 children, the occurrence 

 of adenoid growth was more frequent in boys than in girls. On the 

 average, 6 per cent of boys and girls from 4 to 18 years of age showed 

 pronounced adenoid growth. The ratio of the percentage of girls to 

 the percentage of boys having the defect had an average value of 0.68; 

 for every 100 boys affected there were only 68 girls similarly affected. 

 Analysis of the World's Fair hearing test records shows that 7 per cent 

 of boys and girls from 10 to 19 years of age are deafened for a 7040- 

 cycle tone to the extent of the 2<y limit described in the previous section. 

 The ratio of the percentage of deafened girls to the percentage of 

 deafened boys is 0.75, or 75 girls for every 100 boys. Although it 

 should not be concluded that the similarity of these ratios establishes 

 a correlation between adenoid growth and high-tone deafness, it is 

 believed that they are sufficiently suggestive to justify further study 

 of these defects. 



Acknowledgment 



This survey was made possible by the cooperation of a large number 

 of people in many parts of the Bell System. The planning, design, 

 and construction of the exhibit were shared by the American Tele- 

 phone and Telegraph Company, The Western Electric Company, 

 Electrical Research Products, Inc., and Bell Telephone Laboratories, 

 Inc., and to them the authors are indebted. We wish to express our 

 gratitude to the Pacific Telephone and Telegraph Company and the 

 New York Telephone Company for their efificient operation of the 

 exhibits and for the large share which they had in obtaining the data 

 used in the survey; to the tabulating and mathematical groups at 

 the Laboratories for many hours of painstaking labor in treating 

 the data; and to many of our associates whose suggestions and 

 criticisms were a valuable aid in the analysis of the information. We 

 also wish to express our appreciation to the large group of interested 

 visitors to the Fairs whose participation in the hearing tests constituted 

 the basic material of this survey. 



21 "The Health of the School Child," Public Health Bulletin 200, Table 46, page 

 141, United States Public Health Service, Wash., D. C. W. Franklin Chappel, "Ex- 

 an ination of the Throat and Nose of 2000 Children," Jour, of Med. Sciences, 97: 

 148-154 (1889). Wm. R. P. Emerson, "Physical Defects in 1000 Children," Amer. 

 Jour, of Diseases of Children, 33: 771-778 (1927). 



