4.1 Comparison with the existing literature
In South Korea, the NHIS covers only one hearing aid for
hearing-disabled patients registered with the Ministry of Health and
Welfare, who can but the other hearing aid at their own expense. So, we
often encounter a lot of patients who can buy only one hearing aid. For
monaural amplification in AHL, two questions are useful in selecting the
ear to be aided. (1) If the better ear is aided, can aided hearing
improve audibility as well as communication for the AHL patient? (2) If
the worse ear is aided, can aided hearing make a patient understand
speech better in quiet as well as in noise and provide advantages of
binaural hearing? Empirically, UHL seems to be suitable for monaural
amplification but AHL1 is likely to be a candidate for binaural
amplification. AHL2 seems to be a dilemma for selection which ear to
amplify monaurally; if worse ear is amplified, binaural symmetry can be
accomplished but both hearing is more likely to be handicapped. If
better ear is amplified, the patient may get only one serviceable
hearing. In the AHL1 and AHL2 subtypes defined in this study, these two
questions should be considered together, but only the second question is
relevant to patients with UHL or SSD. The 60 dB HL rule or Briskey’s
criteria for successful binaural fitting are not enough to offer a
reasonable solution.12