Skip directly to search Skip directly to A to Z list Skip directly to page options Skip directly to site content

NIOSHTIC-2 Publications Search

Search Results

Can infrasound protect the cochlea from a damaging level of noise?

Lee-SC; Bohne-BA; Harding-GW; Salt-AN
Abstr 26th Midwinter Res Meet 2003 Feb; 22:164
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.
Noise-exposure; Exposure-levels; Noise-induced-hearing-loss; Noise-exposure; Noise; Hearing; Hearing-disorders; Hearing-loss; Laboratory-animals; Animals; Cell-damage; Cellular-reactions; Animal-studies
Publication Date
Document Type
Funding Type
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
Source Name
Abstracts of the 26th Midwinter Research Meeting
Performing Organization
Washington University, St. Louis