외이도-유양동-귀뒤바퀴피부 누공환자에서 수술 전, 후의 외이도 공명의 변화

Due to the structure with one end closed, the external ear resonance effect in which the high frequency is amplified can be generated, and the sound can be perceived well. The external ear resonance normally has a first peak and a second peak. On average, the first peak has a gain of 18.6 dB at 2620 Hz and the second peak has a gain of 18.2 dB at 4210 Hz. The resonance of the external auditory canal changes with the state of the tympanic membrane, the presence of the ventilation tube, and the structure (length, diameter, shape) of the external auditory canal. A patient with a postauricular meatomastoid cutaneous fistula was admitted to the hospital with a foreign body which is the molding of the hearing aid. After removal of the foreign body, the resonance of the external auditory canal was lost and the subjective sound cognitive ability decreased. In the case of postauricular meatomastoid cutaneous fistula, we confirmed the improvement of sound cognitive ability, the change of pure tone hearing threshold, and the change of the external ear resonance after reconstruction of the ear canal without middle ear reconstruction. (J Clinical Otolaryngol 2018;29:235-239)