Table 1. Pre- and postoperative Bone conduction thresholds.

Bone Conduction	Preoperation	Postoperation	Z	P
Average(500-4000 HZ)	32.5(23.75~38.75)	25(19.38~31.25)	−6.343	<0.001
250 HZ	25(25~30)	15(10~20)	−6.203	<0.001
500 HZ	25(20~35)	20(15~25)	−6.511	<0.001
1000 HZ	30(25~40)	25(15~30)	−6.397	<0.001
2000 HZ	35(30~45)	30(20~37.5)	−5.547	<0.001
4000 HZ	30(20~45)	25(20~40)	−0.368	0.713