Low-frequency sound’s after-effects arise from calcium homeostasis in outer hair cells

Evidence

Here, we show that the mechanical amplification of hair cells (OHCs) is significantly affected after the presentation of LF sound. First, we show the Bounce phenomenon in slow level changes of quadratic, but not cubic, distortion product otoacoustic emissions (DPOAEs). Second, Bouncing in response to LF sound is seen in slow, oscillating frequency and correlated level changes of spontaneous otoacoustic emissions (SOAEs). Surprisingly, LF sound can induce new SOAEs which can persist for tens of seconds. Further, we show that the Bounce persists under free-field conditions, i.e. without an in-ear probe occluding the auditory meatus. Finally, we show that the Bounce is affected by contralateral acoustic stimulation synchronised to the ipsilateral LF sound. These findings clearly demonstrate that the origin of the Bounce lies in the modulation of cochlear amplifier gain. We conclude that activity changes of OHCs are the source of the Bounce, most likely caused by a temporary disturbance of OHC calcium homeostasis. In the light of these findings, the effects of long-duration, anthropogenic LF sound on the human inner ear require further research. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3701

Categorization

• DEFINE: Defines the Bounce phenomenon as slow oscillating changes in cochlear function after low-frequency sound offset, traced to OHC modulation.
• XREF: Connects to otoacoustic emission literature and cochlear amplifier research; also relevant to noise-exposure and hearing-safety standards. — connects to: Outer hair cells respond better than inner hair cells to low-frequency sound — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 228; Calcium oscillations in outer hair cells drive the hearing Bounce; The SOAE Bounce reflects a calcium-driven homeostatic readjustment in outer hair cells. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3703 (+5 more)
• SHARE: A specific audiologist or hearing researcher would care about the quadratic-but-not-cubic DPOAE asymmetry and the contralateral stimulation effect on the Bounce.
• corroborated: 5 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 3701