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Abstract
Real –Ear - to Coupler Difference (RECD) is the difference in decibels, as a function of frequency, between the SPL at a specified measurement point in the ear canal and the SPL in a 2cc coupler, for a specified input signal (Bohnert and Brantzen, 2004). Different RECD values vary with ear canal volume and middle ear impedance (Martin et al., 2001).
In this study, RECD was obtained using an insertion gain analyzer for 24 adult patients with dry tympanic membrane perforation (31 ears) (group 1) and 20 healthy adult control subjects (40 ears) (group 2) for comparison.
Cases showed moderate conductive hearing loss. The greatest loss was in the low frequencies (250 Hz & 500Hz), followed by the high frequencies (4 KHz & 8 KHz) then the mid frequencies (1 KHz & 2 KHz).
There was no statistically significant difference between anterior and posterior perforations as regards the degree of hearing loss.
Comparison of the RECD between both groups revealed that there was a statistically significant difference of RECD at frequencies 250 Hz, 500Hz and 750 Hz, between both groups. The RECD was 3 to 6 dB lower in group 1 than in group 2.
There was a statistically significant difference as regards the RECD values at frequencies: 250 Hz, 500 Hz, 750 Hz and 1000 Hz between right ears with perforated tympanic membranes and right control ears. Also there was a statistically significant difference as regards the RECD values at frequencies: 250 Hz, 500 Hz and 750 Hz between left ears with perforated tympanic membranes and left control ears.