Prevention of impulse noise-induced hearing loss with antioxidants

Acta Otolaryngol. 2005 Mar;125(3):235-43. doi: 10.1080/00016480410023038.


Conclusion: These findings indicate a strong protective effect of ALCAR and NAC on impulse noise-induced cochlear damage, and suggest the feasibility of using clinically available antioxidant compounds to protect the ear from acute acoustic injury.

Objective: Reactive oxygen species have been shown to play a significant role in noise-induced hearing loss. In the current study, the protective effects of two antioxidants, acetyl-L-carnitine (ALCAR) and N-L-acetylcysteine (NAC), were investigated in a chinchilla model of hearing loss resulting from impulse noise. It was hypothesized that pre- and post-treatment with these antioxidants would ameliorate the effects of impulse noise compared to saline-treated controls.

Material and methods: Eighteen animals were randomly assigned to 1 of 3 groups and exposed to impulse noise at a level of 155 dB peak SPL for 150 repetitions. ALCAR or NAC were administered twice daily (b.i.d.) for 2 days and 1 h prior to and 1 h following noise exposure, and then b.i.d. for the following 2 days. For the control group, saline was injected at the same time points. Auditory brainstem responses (ABRs) were recorded. Cochlear surface preparations were made to obtain cytocochleograms.

Results: Three weeks after exposure, permanent threshold shifts for the experimental groups were significantly reduced to approximately = 10-30 dB less than that for the control group (p < 0.01). Less hair cell loss was also observed in the ALCAR and NAC groups than in the control group.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acetylcarnitine / pharmacology*
  • Acetylcysteine / pharmacology*
  • Animals
  • Antioxidants / pharmacology*
  • Chinchilla
  • Disease Models, Animal
  • Evoked Potentials, Auditory, Brain Stem / drug effects
  • Female
  • Hair Cells, Auditory / drug effects
  • Hair Cells, Auditory / pathology
  • Hearing Loss, Noise-Induced / prevention & control*
  • Recovery of Function / drug effects


  • Antioxidants
  • Acetylcarnitine
  • Acetylcysteine