The Effect on Acoustic Characteristics of Surgical Modification of the External Ear / 대한이비인후과학회지

ABSTRACT

BACKGROUND AND OBJECTIVES: The peak resonance corresponds to the fundamental frequency whose wavelength is approxi-mately four times the canal length and is between 2 and 3 kHz in a normal ear canal. The possibility that creation of an open cavity mastoid alters the acoustical characteristics of the external ear has been suggested. The aim of this study was to ascertain the acoustical changes in the external auditory canal occasioned by the open cavity mastoidectomy, and compare it with the mastoid obliteration. MATERIALS AND METHODS: We measured the external ear resonance (EER) characteristics in 40 normal ears, 20 ears with open cavity mastoid and 40 ears with obliterated mastoids. The EER characteristics were measured using 6500 hearing aid test system. RESULTS: The means of the peak resonant frequency and the peak amplitude at open cavity mastoids (2350 Hz, 18.5 dB) showed significant differences (p<0.1) when compared with those at normal mastoids. However, the means at obliterated mastoids (2850 Hz, 20.5 dB) recovered to the near normal state. CONCLUSION: While the open cavity mastoidectomy can affect the resonance frequency, the mastoid obliteration may help anatomical reconstruction as well as acoustical recovery.