The Effects Of Tympanic Membrane Perforation On Real-Ear To Coupler Difference

OBJECTIVE To investigate the effects of adults' tympanic membrane perforation on Real-Ear To Coupler Difference in order to provide some reference for hearing aids fitting.METHOD RECD was measured using AudioscanRM500 in 34 ears with dry tympanic membrane perforation, and 33 normal ears which is served as controls. SPSS software was used for statistics analysis . RESULT There is significant difference (p<0.05) below lkHz(including 1kHz) and in 4kHz between experimental group and control group. In perforated ears, the RECD was up to 3.5— 15dB smaller compared to normal ones in the frequency range from 250Hz to 1kHz, the values of RECD was negative from 250Hz to 750Hz.A larger standard deviation was found in experimental group. The mean intra-subject standard deviation was 4.4dB in experimental group compared with 1.4dB in control group. The equivalent ear canal volume appeared to be negatively correlated with the RECD reduction below 0.75kHz and that did to be no correlation above lkHz,the more the equivalent ear canal volume, the smaller the RECD. The effects of the size of tympanic membrane perforation on RECD was found to have no significant difference.CONCLUSION RECD of dry tympanic membrane perforation was more lower than normal subjects, Real-Ear measurement should be carried out individually rather than using the age-appropriate average values when hearing aids fitted for these patients, In fitting hearing aids low frequency gain should be increased appropriately in patients with tympanic membrane perforation.