抄録
The audiograms obtained by the practicing clinician and those taken in the departments of otorhinolaryngology of large medical institutions or research centers often show considerable discrepencies in the results. Even tests of the hearing function of the same individual at separate reliable departments of university hospitals may show dissimilar audiograms. Thus the reliability and objective value of such hearing tests have come to be questioned and debated.
As examination of the hearing acuity relies upon the subjective response of the individual being tested and as the results are greatly influenced by variable physiologic factors, some difference in the results cannot be avoided. It is however worthwhile to consider and discuss the various factors that might produce discrepencies in the audiogram in order to pinpoint some of the causes that could be corrected and the precautionary measures that must be taken to obtain as nearly as possible a reliable and accurate audiogram.
Periodic testing and calibration of the audiometer, gentle handling and correct application of the receiver, the effect of background noise, and the use of interrupted tones are obviously important.
Introduction of attenuation in steps of 5 db/sec is best, and initial audiograms of patients at both extremes of age are not reliable. Because of variation in hearing acuity during different periods of the day, tests should preferably be repeated at the same time of day as previously. Audiograms taken in surroundings where the background noise level is high or when TTS due to noise is suspected are worthless. As audiometry is an examination of the sense of hearing, the results should not be interpretated simply as in other objective tests or else considerable errors might be introduced.
The above points have been found important for accurate operation and interpretation of audiometric examinations and are stressed in the present paper.
