Open-cavity mastoid surgery: its effect on the acoustics of the external ear canal.

Temporal bone studies have demonstrated that a modified radical mastoidectomy changes the resonant characteristics of the external auditory canal, but the effect has not been reported in patients. In 12 patients, performing open-cavity mastoid surgery for cholesteatoma changed the mean peak resonant frequency of the external ear canal from 2.5 to 2.2 kHz (p less than 0.02). This is in comparison with creating a modified radical mastoid cavity in 6 temporal bones which changed the mean peak resonant frequency of the external ear canal from 3.9 to 1.9 kHz. It is concluded that open-cavity mastoid surgery in patients changes the acoustics of the external ear canal less than in temporal bone studies.