Statistical Observation of Variation of Hearing Threshold of Air Conduction

One hundred and eighty-two cases of occupational deafness were selected as subjects of this study, and variation of hearing threshold of air conduction were statistically observed mainly with the left side ears. The results of the experiments are as follows:1) No clear correlation was noticed between the average hearing loss and variation of hearing threshold.2) As to tinnitus and variation of hearing threshold, no significant difference was found between continuous tinnitus, intermittent tinnitus and no tinnitus.3) As to variations of hearing threshold obtained by comparing hearing threshold of the first test with that of the second, and the second with the third, etc., significant differences were noticed only at 1, 000Hz, 2, 000Hz and 4, 000Hz.4) When variations of hearing threshold were examined at various frequencies, no significant differences were found.5) Mention was also made of qualifications of technicians who measures auditory acuity.