XVIII Hearing Testing Cabinet

Abstract

Our postwar planning should include some thought for improving our detection of the loss of hearing. The cabinet to be described has been in my office for some time and has some useful points which seem worthy of description.The cabinet should not be called soundproof because that term must be reserved for rooms built solidly of hollow blocks with a soundproof door, well insulated, and with no noisy pipes running through the walls. However, for the average private office sufficient sound is screened out by this type of cabinet so that the lesser hearing losses may be detected. The hearing tests usually conducted in the average office will not be sufficiently accurate to detect losses below 20 to 30 decibels, particularly when a masker is used since that usually lowers the curve about 10 decibels. The use of this cabinet alone with a rubber padded receiver on each ear and no masker allows the detection of heating at the zero line when it is present.The receivers are connected by a head band and fit tightly over the ears. The phone over the ear not being tested may be used as a masker when the tone being tested becomes so loud that it is heard by the operator through the room or a shadow curve of the other ear may be suspected.As a rule the responses which result from testing children under eight years of age (depending upon their alertness) are not so reliable when done with the average equipment. However, with a light placed in front of the patient, connected with another over the audiometer and both operated simultaneously by a push button on a cord, more accurate responses are obtained. These lights work off the city current and are independent of the audiometer with all the wiring and fixtures connected with the lower half of the back of the cabinet. The patient is asked to keep the light in front of him lit as long as he hears the tone being tested. Thus a great deal of unintentional flickering of the light is avoided and more reliable responses result, particularly in children as young as six years of age.