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ABSTRACT: To investigate the effects of tympanic membrane perforation on real-ear to coupler difference (RECD) in adults.
RECD was measured in 34 ears with dry tympanic membrane perforation, 34 normal subjects served as controls.
There was significant difference (P<0.05) below 1 kHz (including 1 kHz) and in 4 kHz between experimental group and control group. For perforated ears, RECD was 3.5-15 dB less from 250 Hz to 1 kHz while the values of RECD was negative from 250 Hz to 750 Hz. A larger standard deviation was found in experimental group. The mean intra-subject standard deviation was 4.4 dB in experimental group as contrasted with 1.4 dB in control group. The equivalent ear canal volume appeared to be negatively correlated with the RECD reduction below 0.75 kHz and no correlation above 1 kHz. The more the equivalent ear canal volume, the smaller the RECD. It was found that the size of tympanic membrane perforation had no effect on RECD.
It is recommended to perform real-ear measurement individually instead of using the age-appropriate average values, and to increase low frequency gain appropriately when fitting hearing aids for patients with dry tympanic membrane perforation.
Lin chuang er bi yan hou ke za zhi = Journal of clinical otorhinolaryngology 04/2008; 22(7):303-5.