Simulated hearing loss isolates audibility from other hearing-loss effects

Evidence

Stimuli were presented over equalized headphones and for HI listeners had different levels of (linear) amplification applied to systematically vary audibility: amplification according to NAL-RP, NAL-RP plus 25 % of extra gain (i.e. on top of NAL-RP), and NAL-RP plus 50 % of extra gain. An extra gain of 100 % would have restored normal audibility, but was impossible to achieve due to loudness discomfort. Given the sloping hearing loss, an increase in amplification mainly resulted in an increased high-frequency gain and thus in an increase in audible bandwidth. NH subjects were tested at the same audibility levels. This was realized by first applying attenuation filters that mimicked the average audiogram of the HI subjects and then applying the same gains as described above. No other aspects of hearing loss were considered. — Dijk, Pim van, Physiology, Psychoacoustics and…, 1746

Subjects were seated in an audiometric booth and repeated the target sentences to a conductor. Stimuli were presented over equalized headphones and for HI listeners had different levels of (linear) amplification applied to systematically vary audibility: amplification according to NAL-RP, NAL-RP plus 25 % of extra gain (i.e. on top of NAL-RP), and NAL-RP plus 50 % of extra gain. An extra gain of 100 % would have restored normal audibility, but was impossible to achieve due to loudness discomfort. Given the sloping hearing loss, an increase in amplification mainly resulted in an increased high-frequency gain and thus in an increase in audible bandwidth. NH subjects were tested at the same audibility levels. This was realized by first applying attenuation filters that mimicked the average audiogram of the HI subjects and then applying the same gains as described above. No other aspects of hearing loss were considered. — Dijk, Pim van, Physiology, Psychoacoustics and…, 1721

Categorization

• DEFINE: Full audibility restoration (100 percent gain) would exceed loudness discomfort, capping achievable HI amplification.
• QUESTION: Loudness discomfort caps hearing-aid gain below what would restore normal audibility - does this itself explain residual SRM deficits in aided HI listeners?
• corroborated: 3 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 1746; Dijk, Pim van, Physiology, Psychoacoustics and…, 1721