High-side two-tone suppression is lost in some hearing-impaired fibers but low-side suppression persists.

Evidence

For NH fibers, high-side 2TS was always observed (Fig. 3a ). However, in 6 of 35 HI fibers, we could not detect significant high-side 2TS (Fig. 3b ). These fibers have very broadened excitatory tuning (Fig. 3c ). In HI fibers with detectable high-side 2TS, the dB difference between excitatory threshold and suppressive threshold was not greater than observed in NH fibers (Fig. 3d ). For many fibers high-side-2TS threshold was within 20 dB of on-CF excitatory threshold. Low-side 2TS-threshold estimates are surprisingly low (Fig. 3a and b ). All fibers had low-side suppressive regions, regardless of hearing status, typically in the region of 0- to 20-dB SPL. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3816