Low-frequency sound triggers larger cochlear responses than comparable higher frequencies.

Evidence

For decades, low-frequency sound, i.e. sound with frequencies lower than 250 Hz (Berglund et al. 1996 ), has been considered to largely bypass the inner ear even at intense levels, simply because human hearing thresholds for frequencies below 250 Hz are relatively high. Recent evidence from animal models shows that physiological cochlear responses to LF sound are even larger than those evoked by equal-level, higher frequencies in the more sensitive range of hearing (Salt et al. 2013 ). No data for human subjects are available, but, considering the higher sensitivity of humans for LF sounds, similar results can be expected (Salt et al. 2013 ). … Perceptual thresholds essentially reflect the sensitivity of inner hair cells (IHCs), which are functionally coupled to inner ear fluids (Nowotny and Gummer 2006 ; Guinan 2012 ). IHCs are therefore sensitive to basilar-membrane velocity, which decreases with decreasing frequency. OHCs, in contrast, are mechanically linked to both the basilar membrane and the tectorial membrane. OHCs are therefore sensitive to basilar membrane displacement (Dallos et al. 1982 ; Dallos 1986 ), which does not decrease with decreasing stimulus frequency. Thus, OHCs are more sensitive to LF sound than IHCs and it is this difference in LF sensitivity, which contributes to the LF limit of sound perception (Salt and Hullar 2010 ; Salt et al. 2013 ). — Dijk, Pim van, Physiology, Psychoacoustics and…, 3704

Categorization

• DEFINE: Defines the IHC vs OHC transduction distinction (velocity vs displacement sensitivity) which is load-bearing for the whole chapter.
• CANDY: The surprising finding that LF sound drives cochlear responses larger than equal-level mid-frequency sound is a striking elevator fact.
• corroborated: 2 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 3704
• XREF: connects to: Physical frequency is the wrong scale for describing inner-ear effects; Perceptual insensitivity to low-frequency sound masks its physiological impact on the inner ear; Outer hair cells respond better than inner hair cells to low-frequency sound — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 228 (+4 more)

Broader Connections

• Ear frequency response varies with amplitude, especially at low frequencies. #expands (0.88)
• Auditory sensitivity varies nonuniformly across the frequency range #expands (0.80) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 648