Korean J Otolaryngol-Head Neck Surg.
2001 Feb;44(2):148-152.
Changes of external ear resonance before and after surgery in chronic otitis media
- Affiliations
-
- 1Department of Otorhinolaryngology, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul, Korea.
- 2Department of Otolaryngology, Hanil General Hospital, Seoul, Korea.
Abstract
-
BACKGROUND AND OBJECTIVES: External ear resonance (EER) can normally increase the sound pressure level at the tympanic membrane by as much as 20 dB at the frequency between 2 and 4 kHz. Perforation of tympanic membrane (TMP) may alter the resonance characteristics. Surgical modifications of the external auditory canal by tympanoplasty may also change the EER features. We aimed to analyze the EER of patients with the TMP before and after surgery.
MATERIALS AND MEHTOD: This study comprised of 130 patients (135 ears) with chronic otitis media. We checked EERs before and after the surgery. The preoperative group was divided into two groups according to perforation size. Postoperatively, the EER was checked at 3, 6, 9, 12 months or after 15 months. We compared these data with the control group which comprised of 96 adult ears.
RESULTS
In the preoperative group, the peak resonant gain and the frequency were not different from the control's and the peculiar negative peaks appeared around 1500 Hz in half of the cases. No significant differences were found in the first peak gains according to the perforation size. The negative peaks appeared deeper in the larger perforation group. After tympanoplasty, the gain markedly increased. As time passed, the gain tended to decrease, but did not equalize with the control's data.
CONCLUSION
Additional gain should be considered in the frequency of around 1 kHz for hearing aid users with the TMP. We could expect alterations of EER after tympanoplasty, suggesting that these changes should be considered at the time of fitting hearing aids.
