Can infrasound protect the cochlea from a damaging level of noise

Details

• Personal Author:
  Bohne BA ; Harding GW ; Lee SC ; Salt AN
• Description:
  Infrasounds (ie, < 20 Hz for humans; < 100 Hz for chinchillas) are not audible, but they produce large movements of cochlear fluids (Salt & DeMott, 1999). It was speculated that infrasound might bias the basilar membrane & perhaps minimize noise-induced hearing loss (NIHL). Chinchillas were simultaneously exposed to a 30 Hz tone at 100 dB SPL & a 4-kHz OBN at either 108 dB SPL for 1.75 h or 86 dB SPL for 24 h. One tympanic membrane (TM) was perforated prior to exposure to attenuate infrasound transmission to that cochlea. Controls were exposed to infrasound or the 4-kHz OBN only. ABR threshold shifts (TS) & DPOAE level shifts (LS) were determined post-TM-puncture & immediately post-exposure, just before cochlear fixation. The cochleae were dehydrated, embedded in plastic, dissected as flat preparations & evaluated for hair-cell (HC) losses. For each animal, the magnitude & pattern of functional & HC losses were compared between their right & left cochleae. The infrasound exposure alone resulted in a 10-20 dB TS below 1 kHz, no LS & no HC damage/loss. Exposure to the 4-kHz OBN alone at 108 dB produced a 50-60 dB TS for 1-16 kHz, a 40-50 dB LS for 2-12 kHz & severe OHC loss in the middle of the first turn. When infrasound was added, the functional and HC losses extended much farther apically & basally than for the 4-kHz OBN alone. Exposure to the 4-kHz OBN alone at 86 dB produced a 40 dB TS for 3- 12 kHz & 30 dB LS for 3-8 kHz, but no HC loss in the middle of the first turn. When infrasound was added, no differences in the functional and HC losses were found compared to the 4-kHz OBN alone. We hypothesize that exposure to infrasound & an intense 4-kHz OBN increases cochlear damage because the large fluid movements from infrasound cause more intermixing of cochlear fluids through the damaged reticular lamina. Simultaneous infrasound & a moderate 4- kHz OBN did not increase cochlear damage because the reticular lamina rarely breaks down during this exposure. [Description provided by NIOSH]
• Subjects:
  Animals Hearing Hearing Loss Hearing Loss, Noise-Induced Laboratories Noise Occupational Health Safety
• Keywords:
  Animal-studies Cell-damage Cellular-reactions Exposure-levels Hearing-disorders Hearing-loss Laboratory-animals Noise-exposure Noise-induced-hearing-loss
• ISSN:
  0742-3152
• Publisher:
  Association for Research in Otolaryngology
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Abstract or Summary
• Place as Subject:
  Florida ; Missouri ; New Jersey ; OSHA Region 2 ; OSHA Region 4 ; OSHA Region 7
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  26
• NIOSHTIC Number:
  nn:20041607
• Citation:
  Abstr Midwinter Res Meet Assoc Res Otolaryngol 2003 Feb; 22:164
• Editor(s):
  Santi PA
• Federal Fiscal Year:
  2003
• NORA Priority Area:
  Disease and Injury: Hearing Loss
• Performing Organization:
  Washington University, St. Louis
• Peer Reviewed:
  False
• Start Date:
  20000401
• Source Full Name:
  Abstracts of the 26th Midwinter Research Meeting of the Association for Research in Otolaryngology, Febuary 22-27, 2003, Daytona Beach, Florida
• End Date:
  20130914
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:49a319b86867ed147324c712c3c50b6eaa0443825b0bd119fcdb7a20e4e2c1eb499ebf44463e0bb757299d0871c58ceda54a520c90d3cb88f32efc89c41d86a1
• Download URL:
  https://stacks.cdc.gov/view/cdc/194121/cdc_194121_DS1.pdf
• File Type:
  [PDF - 364.52 KB ]