NO ESCAPE FOR MALINGERERS.

Wanganui Chronicle, Volume LXVI, Issue 17571, 15 May 1919, Page 7

NO ESCAPE FOR MALINGERERS.

AN INGENIOUS APPARATUS WHICH MUST CATCH ONE WHO PRETENDS PARTIAL DEAF-

NESS

It was an observation of the ancients that the greater pain obscures the less, and that in a general way, strong sensations prevent the appie-l ciation of weaker ones. In preaise terms, stimuli that are similar in till their properties except intensity t,re ! not dissociated by the mind, only the stimulus of greater intensity being so registered that we ar^ conscious of it. This law was r.tiUsed with much success by Dr. .fohi F. Callahan, of Brockton, Mags, in the detection of malingerers who sought to evade the draft by false claims of ! deafness in one ear—a common practice. ' When a sound reaches each rar with the same intensity we are conscious of hearing it in both. Whan it reaches each ear with different iat.eesities we are conscious of heaving it only in the ear where intensity is the greater. Thus tuning forks vibrating with the same pitch and i loudness one inch from each cac are heard in both ears: but if the fork at the left ear is removed to a point three inches away this sound is losi, and only the fork remaining at the ! right ear is heard. But if now, the j latter is put six inches back, it will no linger be heard, while the left | ore, formerly not sensed, will beicome audible. Getting the trap. Dr. Callahan early convinced himself that tests which depend upon the suspected malingerer not knowing in which ear he hears the test ! sounds are an insult to his intelligence; the patient can successfully concentrate his attention on his good ear and suppress what he hears in his supposedly bad ear. The most we could here expect would be to trick a' patient who was not very sharp; and even then we could merely ascertain that he was not fatally deaf in his " bad " ear—we could never determine the extent of hearing he had in that ear. So Dr. Callahan has worked out a procedure where the patient knows he is betrayed by his ignorance Of which one ought to do it if his claim were correct. ' • The sound is brought to the Patient's ears through rubber tubes. It is necessary to eliminate the pasaibility of bone conduction, sinse the vibration in the tubes can often oe felt with the hand. So instead of being attached to the patient's head with lugs, the tube-ends terminate in a curved arm attached to the^^etiairtop; and after the patient is seated, these ends are brought to within an inch of his either ear, without any contact between him and the apparatus. i The sound may be produc3d in various ways. Dr. Callahan has used tuning forks, and a megaphone manufactured from an old ether cone. In the former case, the desired length of tube is got by a metal clip joining the two tubes, which at the same time makes it possible to use a single fork; and the parts of the tufjes beyond the clip simply do not figure in the test. In the vocal test, where the cone has actually to be at tfrs physical end of both tubes, metal couplings and auxiliary tube-'engths are used. In either event the mechanical details are sufficiently obvious, i HOW IT WORKS. If the patient has two good ears, when the tubes are of the same length he will hear the sound in both ears. There will be a neutral zona of two or three inches around this point in which the. same result will be obtained. But the minute either tube becomes appreciably longer than the other, audibility will be con-