Table 2. Pre- and postoperative Air conduction thresholds.

Air Conduction	Preoperation	Postoperation	Z	P
Average(500-4000 HZ)	58(50~70)	39(33~46)	−6.038	<0.001
125HZ	60(50~65)	35(30~45)	−5.662	<0.001
250 HZ	60(50~70)	35(30~45)	−6.303	<0.001
500 HZ	60(55~75)	35(30~45)	−6.365	<0.001
1000 HZ	65(55~75)	35(30~50)	−6.156	<0.001
2000 HZ	55(45~75)	40(30~50)	−5.708	<0.001
4000 HZ	50(35~85)	40(30~60)	−4.391	<0.001
8000 HZ	60(40~85)	60(40~80)	−.164	0.870