Efficacy of the antioxidant N-acetylcysteine (NAC) in protecting ears exposed to loud music

J Am Acad Audiol. 2006 Apr;17(4):265-78. doi: 10.3766/jaaa.17.4.5.


Antioxidants have been reported to be effective in reducing acoustic trauma in animal models but have not been studied in humans. In this study, the antioxidant N-acetylcysteine (NAC) was evaluated to determine if it would reduce temporary changes in auditory function as a result of exposure to loud music in humans. Pure-tone thresholds and distortion product otoacoustic emissions (DPOAEs) were collected in 31 normal-hearing participants, using a randomized, double-blind, placebo-controlled design, before and after two hours of live music in a nightclub. Using repeated measures analysis of variance, no statistically significant differences were found between participants who received NAC versus a placebo for any of the outcome measures. Across all subjects, the largest pure-tone threshold shift occurred at 4 kHz. DPOAE measures were characterized by reductions in amplitude and a trend for shorter group delay values. When the 3 and 4 kHz data were examined by imposing specific criteria of greater than 2 dB DPOAE amplitude reductions and 10 dB or greater pure-tone threshold shifts, DPOAE reductions occurred more often at 3 kHz, and pure-tone shifts occurred more often at 4 kHz.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Acetylcysteine / administration & dosage
  • Acetylcysteine / pharmacology*
  • Adult
  • Antioxidants / administration & dosage
  • Antioxidants / pharmacology*
  • Audiometry, Pure-Tone
  • Auditory Threshold / drug effects*
  • Double-Blind Method
  • Female
  • Hearing Loss, Noise-Induced / prevention & control*
  • Humans
  • Male
  • Noise / adverse effects
  • Otoacoustic Emissions, Spontaneous / physiology


  • Antioxidants
  • Acetylcysteine