Comparison of Coupler Gain with Real Ear Insertion Gain

You, Kyoung; Lee, lunghak

ORIGINAL ARTICLE

Commun Sci Disord. 2002;7(3): 179-189.

Kyoung You^` , and lunghak Lee^`

유경(Kyoung You)| 이정학(lunghak Lee)

ABSTRACT

In this study, the real ear insertion gain(REIG) was compared with the coupler(HA-2 coupler) gain. The REIG is different from the coupler gain for several reasons. The coupler gain typically exceeds the REIG because it is affected by head, pinna, concha diffraction (i.e., the microphone location effect), and because the volume of the residual ear canal is smaller than 2cc coupler(i.e., RECD effect). Subjects for the study were 12 adults and 10 children. The degree of hearing loss ranged from mild to severe. Ear canals of the subjects were free of cerumen and the middle ear functions were normal. They were all wearing behind-the-ear hearing aids. The abbreviation CORFIG stands for Coupler Response for Flat Insertion Gain. The value can be used to find a coupler gain that is equivalent to a certain REIG. To predict the amount of REIG, the CORFIG is subtracted from the 2cc coupler gain. The mean CORFIGs for children were -5.38 dB at 200 Hz, -1.93 dB at 500 Hz, -1.2dB at 1000Hz, 2.01dB at 2000Hz, 10.03dB at 4000Hz. For adults the values were -1dB at 200Hz, 0.33dB at 500Hz, 2.53dB at 1000Hz, 6.6dB at 2000Hz, 14.27dB at 4000 Hz. Once getting the individual CORFIG value across frequencies, it would be possible to predict the REIG from the 2cc coupler gain. Thus, the use of the CORFIG may reduce the errors of inappropriate hearing aid fitting.