Analysis of the Cause of Auditory Errors in Pure Tone Threshold Value Tests

Abstract

The condition which mostly affects the threshold value in the pure tone test is background noise. For that reason, comparison of the test results from various testing institutes is not reasonable. It is obvious, however, that there are differences which are not negligible among the test results even from examination rooms with less than 50dB A, which satisfy the condition advised by ISO for a quiet room. Therefore, we used several audiometers (ISO) of the same quality and they are calibrated at the same intervals, and we selected several experienced and inexperienced persons as examiner and examinee. The factors such as the pressure of the earphone, rotation speed of the attenuator and seriousness of the examiner and examinee were analysed to elucidate the cause of the errors appeared on audiograms.
As the result, there was always an error of 2.88dB depending on the audiometerc equipments including the receiver, even though the strictly corrected audiometer was used. The other factors, while the individual one was small, contributed to increase the error approx. to 8.52dB when they were added, and even though the background noise was of the same level and tone, approx. 10dB difference, depending on the testing institute, could be existed.