152 Prevention o£ Deafness 



parents to have good hearing. We found, however, that only 58.8 per cent 

 have normal hearing for all tones; 36.3 per cent have impaired hearing for 

 the three or four octaves at the upper end of the scale, with normal hearing 

 for all lower tones and for the voice— in quiet surroundings. This picture- 

 impaired hearing for high tones with good hearing for low tones and for the 

 voice in a quiet place— is identical with the common type of partial deafness 

 in old age. Elderly people may understand conversation perfectly if the fre- 

 quencies used in speech (250 to 3,500 d.v.) are not masked by other voices or by 

 the roar of traffic. Under the latter conditions, however, they have difficulty 

 in understanding unless the speaker raises his voice above the decibel level 

 of the surrounding sounds. All of us with normal hearing throughout the 

 entire scale would be similarly handicapped in noisy surroundings if we had 

 not unconsciously trained ourselves since childhood to interpret properly the 

 overtones of words, just as a stenographer in reading her notes interprets 

 shorthand symbols. Most of our city schools are on streets with heavy traffic, 

 and children with impaired hearing for only the higher frequencies have diffi- 

 culty in hearing the teacher when there is a background of noise in the class- 

 room. This leads in many instances to an erroneous diagnosis by the teacher 

 of indifference, stupidity, or mischievousness, and explains their failure to do 

 well in their school work. 



Lymphoid hyperplasia in the pharynx and nasopharynx is responsible for 

 ear infections, and through interference with the ventilating function of the 

 Eustachian tubes is an important cause of impaired hearing in childhood. 

 Thousands of children would be spared the disabilities of impaired hearing 

 and other complications of enlarged and infected lymphoid tissue, if we un- 

 derstood better the basic problem of why some children are more susceptible 

 than others to respiratory infections, and knew more about the relation be- 

 tween allergy, dietary deficiencies, and ductless gland disorders to lymphoid 

 hyperplasia. The cause could then be corrected at the source, and it would 

 rarely be necessary to remove tonsils and adenoids or operate for infected 

 ears. A large percentage of childhood deafness is caused directly or indirectly 

 by hypertrophy and infection of lymphoid tissue in the nasopharynx. Infec- 

 tions are easily recognized and as a rule are adequately treated with chemo- 

 therapy and operation. The greatest danger to the hearing during childhood is 

 partial or intermittent closure of the Eustachian tubes by hypertrophied nod- 

 ules of lymphoid tissue in and around their pharyngeal orifice, and the thick 

 mucous secretion that accumulates in the tubes, the middle ear, and in the 

 pneumatized spaces throughout the temporal bones. These changes in the 

 middle ear and tubes are not associated with pain, sudden loss of hearing or 

 other symptoms that would direct the attention of the child, the parents, or 

 the family physician to the ears. The earliest evidences are retraction and 

 opacity of the tympanic membranes and impaired hearing for the tones above 

 8,000 d.v. The hearing defect at this stage can be demonstrated only with the 

 audiometer. Impaired hearing for the high tones is also due to causes that 



