Deafness due to loud noises from weapons and explosions is one of the most common disabilities in the US military currently. This is true despite decades of hearing conservation efforts aimed primarily at mechanical personal hearing protection devices (HPDs). While HPDs are essential, they have inherent limitations that explain why, despite their use, noise-induced deafness still plagues the military. As an additional layer of protection to HPDs, we have discovered that a combination of two medicines, a nitrone (HPN-07) with an antioxidant [N-acetylcysteine (NAC)] substantially reduces permanent hearing loss due to explosions or high level continuous noise when given as a treatment after loud sound exposure in rodents. Recent preliminary studies in humans suggest oral NAC alone can reduce noise-induced hearing loss partially. HPN-07 plus NAC together appear to work synergistically in a rodent model of noise-induced hearing loss and thus could be much more effective than NAC given by itself. Both NAC given orally and HPN-07 when given intravenously have been shown to be well tolerated and safe in human subjects. The purpose of the study is to determine the safety, tolerability, and plasma exposure of HPN-07 administered orally in single doses in young healthy male subjects either with or without oral NAC. The Food and Drug Administration (FDA) will want to know that, although HPN-07 is safe when given intravenously, it will also be safe when given by mouth and with NAC. Sufficient animal data exist to strongly suggest that the HPN-07/NAC combination would effectively reduce hearing loss in humans, and clinical data demonstrate some efficacy for NAC by itself in a factory setting and a military setting. NAC is FDA-approved for other indications of use and is exceptionally well tolerated and safe. HPN-07 has been through FDA Phase III trials as an intravenous stroke drug and was found to be very safe in doses higher than we anticipate using. However, oral safety and safety in combination with NAC need to be established for HPN-07. This study would be performed to FDA standards, with volunteer subjects, in a hospital setting with careful monitoring and observation, by an organization experienced in this sort of work, after approval from multiple scientific and ethical bodies. Subject safety would be the utmost priority. Risk is reduced because these medicines have already been used in humans safely; they are not new chemicals that have never been given to people before. The overreaching aim for the research being pursued is to develop a safe and effective orally administered treatment to reduce permanent hearing loss due to combat and training relevant damaging noise. This is the first clinical step in that process. Namely, we want to establish the safety of the administration of this compound orally with and without NAC to satisfy the safety concerns of the FDA to allow progression to FDA Phase II testing as the next step. Phase II testing studies effectiveness in reducing hearing loss as well as additional safety aspects. Proving the clinical safety and efficacy of this treatment combination will give the Department of Defense an additional critical component for its hearing conservation program and has the potential to substantially reduce permanent hearing loss and disability due to both noise and explosions. This approach has significant potential to reduce military disability, personnel loss, and retraining costs, while at the same time improving warfighter effectiveness by reducing hearing loss in theater of operations. The concept would be that after damaging loud noise exposure, a medic in the field could administer this medication to a person sustaining the deafening ear injury. This treatment would immediately begin reducing the degree of hearing loss and enhance the repair processes in the damaged inner ear as a way to restore hearing. It is likely the medication would be taken by mouth for only a few days. Based on a very large amount of safety data we already have for both of these drugs, the risk of side effects would be very low. The medication could also be given prophylactically along with ear plugs when personnel are undergoing extremely loud noise exposure in training. This medication would also be useful in the civilian work force for noise hazardous occupations such as mining, manufacturing, construction, farming, oil-drilling, law enforcement, and others. This medication could also be given to victims with hearing loss after an accidental explosion, loud noise from a deploying automobile air bag, or an explosion from a terrorist attack. Loud noise is the leading cause of deafness in developing countries, and there are currently no effective, FDA-approved therapeutics to treat noise-induced hearing loss. Our therapy could be the first to fill this important role.