목적: It is sometimes difficult to judge whether the stapedial fixation is congenital or a manifestation of otosclerosis, especially for the cases detected at adolescence or early adult period without a sufficient follow up period for detection of progression.We tried to identify, if any, the difference in the audiogram configuration between the two groups to help to diagnose them more correctly. 방법:The congenital stapedial fixation (CSF) group comprised 19 ears from 13 subjects which underwent laser stapedotomy for congenital stapedial fixation before 18 years of age from January 2009 through December 2014.The otosclerosis (OTS) group consisted of 19 ears from 13 subjects which have otosclerosis as documented by surgical findings during laser stapedotomy. To analyze and compare the audiogram configurations between the two groups,we calculated the proportion of Carhart notch as defined by the threshold at 2 kHz minus the mean of thresholds at 1 and 4 kHz (2KBD) and the air bone conduction gap (ABG) at 0.5kHz, 1kHz, 2kHz, 3kHz, and 4kHz from air conduction and bone conduction thresholds at each frequence. 결과:The 2KBD was present in 21.1% (4/19) and 10.5% (2/19) of the CSF group and the OTS group,respectively (p=0.65).The narrowest ABG was identified more frequently in either 3kHz (n=4) or 4kHz (n=7) rather than in 2kHz (n=8) in the CSF group,while the narrowest ABG was predominantly noted in 2kHz (n=15) rather than in either 3kHz (n=4) or 4kHz (n=0) in the OTS group.This trend was statistically significant (p=0.0448).We were not able to identify any single case of OTS that showed the narrowest ABG at 4kHz. 결론:There seems to be a statistical difference in the frequency range where the narrowest ABG takes place between the CSF and OTS groups the shift from 2kHz to 3,4kHz for the CSF group.This enables surgeons to get more aware of the etiology of the patients and to be better prepared for the surgery of conductive hearing loss especially when the preoperative diagnosis is elusive.