NIHL is mostly preventable, and tangible steps to reduce the burden of the disorder can be taken via the implementation of educational programs, regulation, and legislation to raise awareness and pre-emptively mitigate the damage caused by noise. In the US, the 1972 Noise Control Act established federal noise emission standards for commercial products and required that the public be provided information about noise emission levels and ways of reducing them [203]. Two US governmental departments—OSHA and the National Institute for Occupational Safety & Health (NIOSH)—have made recommendations for the permissible noise limit (PEL) of workplace noise exposure based on the average time a worker is exposed [204,205]. Daily noise dose is expressed as a percentage, per occupational standards, taking duration, sound exposure level, and course of exposure into account. For example, reaching 100% of a worker’s daily noise dose could be expressed as 85 dBA per NIOSH and 90 dBA per OSHA over a shift of 8 h. The course of exposure is cut when there is an increase in noise levels [206] (Table 1). Additionally, OSHA regulates that employers must provide hearing protection if employees are exposed to noise over the permissible exposure limit of 90 dB over an eight-hour time-weighted average [207]. Arenas et al. compared the occupational noise exposure levels in Latin America, the US, and Canada and found that 81% of the countries have a PEL of 85 dBA and that the majority of the countries limit impulsive noise exposure to a peak unweighted sound pressure level of 140 dB [208]. However, there were no established regulations in 27% of the countries, potentially exposing millions of people to NIHL.

Environmental noise level is conventionally measured via a sound level meter. However, they are expensive for small businesses and require maintenance and calibration, thereby limiting their widespread implementation. However, smartphone applications for this purpose are now available and provide inexpensive alternatives to specialist calibrated sound meters. An evaluation of the reliability of nine applications found the NIOShH Sound Level Meter to be the most accurate [209]. A free, accessible, and reliable app may help increase compliance with legislation and easy monitoring of environmental noise levels [210]. Additionally, in 2009, the European Commission mandated that output levels in new personal audio devices should be set to a standard of 85 dB, allowing users to increase the volume to a maximum of 100 dB. When users raise the volume to maximum level, a message was required to pop up that warns of the potential for hearing loss.

Hearing protective devices (HPDs) such as earmuffs and earplugs play an important role in protection against noise exposure. Plugs need to be inserted to ensure coverage of the entire ear canal’s circumference to provide protection and minimize irritation. Noise Reduction Ratings (NRRs) are calibrations to assess the protection range of HPDs in a single attenuation value (in dB). Because NRRs are derived via laboratory-based testing, they may overestimate the actual protection provided in non-experimental environments. Therefore, the NRR is derated by 50% on a dB scale before estimating exposure protection [211]. A Cochrane systematic review (2017) of interventions to prevent occupational NIHL found evidence that training on the proper insertion of ear plugs significantly reduced short-term noise exposure but called for more studies on the effectiveness of stricter legislation or better use of hearing protection devices [212]. Additionally, a randomized controlled trial showed that effective training of earplug usage led to significant improvement in the efficacy of HPDs in comparison to the usage of a device with higher NRR [213]. HPD fit-testing systems provide a customized fit for increased attenuation; however, they often require special facilities for testing such as a quiet room or audiometric booth or specialized equipment. Compliance in wearing HPDs is a barrier, especially in the military, as they are thought to decrease auditory situational awareness (e.g., sound detection, sound localization, and speech perception) [211,214]. However, novel fit test techniques (i.e., via a smartphone application) may enable better training and monitoring compliance [211].

Finally, clinicians can actively counsel patients at risk of NIHL on hearing protection strategies and the hazards of noise exposure in the workplace or recreationally (i.e., concerts, sports events, gun ranges, etc.). Simple strategies outlined by the US Centers for Disease Control and Prevention include avoiding exposure to excessive noise, turning down the volume on music, moving away from sources of noise, and using HPDs to reduce exposure to safe levels [215].

There is no cure for NIHL and, to date, no approved pharmacological treatment indicated for its treatment. Although there are currently no clinical practice guidelines specifically for NIHL management, such guidelines exist for sensorineural hearing loss in adults (i.e., from the American Academy of Otolaryngology-Head and Neck Surgery (AAOHNS) [216], American Academy of Audiology [217], and the UK National Institute for Health and Care Excellence [218]) and are applicable. Relevant recommendations include exclusion of conductive hearing loss, audiometric confirmation of sensorineural hearing loss (SNHL) characteristic of noise trauma, and exclusion of retrocochlear pathology in case of asymmetric SNHL based on contrast-enhanced brain MRI or ABR testing. NIHL is clinically managed with hearing aids and/or use of hearing protection during exposure, although if hearing loss worsens, patients may be eligible for cochlear implants [56]. In some cases of acute noise-induced TTS, clinicians may consider the use of intratympanic steroids such as dexamethasone [219,220], although high-quality, long-term efficacy evidence in humans is lacking, and it is not considered for chronic occupational noise exposure. Additionally, the WHO classifies hearing loss into mild, moderate, severe, and profound, listing the typical signs and various recommendations for each level of disability (Box 1). Clinicians can use this classification to educate patients regarding the natural history of NIHL while counseling them on protective measures and the benefits of auditory rehabilitation (i.e., hearing aids or other assistive devices). However, the WHO severity levels are arbitrarily defined, and the system does not address patients with <25 dB hearing level and unilateral hearing loss [221]. Additionally, the speech-in-noise test, which is an effective test for measuring noise interference on speech perception skills, is not considered by the WHO system [222].