A 6-year-old girl was detected hearing loss without subjective complaints by screening audiometry before entering elementary school. The audiogram showed bilateral conductive hearing loss, and repeated pure tone audiometry indicated that right conductive hearing loss was due to ossicular chain abnormality and that left fluctuating conductive hearing loss was due to functional deafness. When she was 11 years old, the audiogram showed bilateral mixed hearing loss, and she was referred to our

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... tient clinic due to progressive hearing loss. Bekesy audiometry revealed type V in the right ear. And there was unexplainable discrepancy between the threshold of pure tone audiometry and response threshold of auditory brainstem response . It was considered that the deterioration of the right hearing loss was due to ossicular chain abnormality and functional deafness, and that of the left hearing loss was due to deteriorated functional deafness. Type Iii-i tympanoplasty was performed on the right ear. After operation, bilateral hearing loss was improved. These observations suggested that a diagnosis of functional deafness with ossicular chain abnormality is difficult, and that various kinds of objective hearing tests are useful for diagnosis of such pathologies.