Deaf-Mutism
may be either congenital or acquired. Two-thirds of all cases will come under the first class, and often depend upon a mal-development of some part of the central nervous system or the ear itself, or may be due to intra-uterine disease of the ear. There is a strong tendency for this disease to be inherited, and particularly in children where there exists a blood-relationship between the parents. The acquired cases may arise from defects in the central nervous system or in the internal ear, or may be due to diseases affecting the middle ear, such as purulent inflammation; and this latter cause is to be noted, as no doubt proper treatment of the middle-ear disease in many cases would have prevented such a result.
All deaf cases become mute, unless the disease has occurred in adult life, when the patient has already acquired the power of language. A deaf-mute does not speak, because he cannot hear, and therefore speech is an unknown quantity.
The TREATMENT would consist in treating any middle-ear disease that might exist, such as the sequelæ of purulent inflammation, and the instruction of the patient in acquiring the power of intercommunication either by the methods long employed of finger-reading, or, much better, by the lip method, so called, where the power of speech is given to the patient. Such cases should attend schools where such instruction is given, commencing at five years of age, and many cases now attest the value of the latter method of instruction.
DIFFERENT METHODS OF DETECTING FEIGNED DEAFNESS.—The Moos Method.—Stop the external canal of the sound ear with a cork; place a vibrating tuning-fork on the head. If the person under examination declares that he does not hear the fork with either ear, he is feigning deafness, as it would be heard well by the sound ear.
The Urbantschitsch method makes use of the human voice. First determine that good hearing power exists in the sound ear; then shut the external canal of this ear with a cork and address the individual with a few loudly-spoken words. If he denies hearing at all, he is feigning, as a good hearing ear, by simple closure of the external canal, will be still able to hear loudly-spoken words.
Another method is to determine the distance at which the person can hear certain words and repeat them correctly. Then have the patient close the eyes and let the examiner try by lengthening and shortening the distance, and note the result. Often he will hear and repeat words spoken at long distances, and apparently not be able to repeat words spoken at short distances.
Müller's Method.—Speak into the sound ear through a tube or paper roll different words as softly and quickly as the examined person can repeat; then let a second examiner repeat the same in the deaf ear. Of course nothing will be heard by the person feigning. Then let the first examiner repeat his performance; the feigner will quickly repeat after him. Suddenly begins the second examiner to softly and quickly speak in the deaf ear, but choosing different words from the first examiner. A really one-sided deaf person will repeat the words spoken into the sound ear only, while the feigner will be in doubt, and will not be able to separate the words heard by both ears, so as only to repeat the words heard by the sound ear.