What can be done to prevent or treat noise-induced hearing loss?

Prevention and Treatment of Noise-Induced Hearing Loss

Primary Prevention: The Only Definitive Treatment

Since noise-induced hearing loss is irreversible once established, prevention through noise reduction and hearing protection must be the absolute priority, as treatment options for established hearing loss are extremely limited. 1, 2

Engineering and Administrative Controls (First-Line Defense)

• Implement engineering controls before relying on personal protective equipment - this includes purchasing quieter equipment, segregating noise sources, and installing sound-dampening panels or curtains around machinery. 2
• Stricter workplace noise legislation can reduce median personal noise exposure by approximately 27.7 percentage points (roughly translating to a 4.5 dB(A) decrease), though this evidence comes from mining industry data with very low-quality evidence. 3
• High-risk industries requiring the most stringent controls include mining and wood products (27% risk), building and construction (23.5%), and agriculture/forestry/fishing (15%). 1
• Entertainment and music industry workers face noise levels of 92-95 dB(A), approximately 4 times higher than legally accepted limits, necessitating aggressive intervention. 1

Personal Hearing Protection Devices (When Exposure Cannot Be Eliminated)

• Hearing protection devices (earplugs or earmuffs) must be used consistently when noise levels exceed permissible limits, reducing noise exposure by approximately 20 dB(A). 2, 3
• Proper insertion training for earplugs improves attenuation by 8.59 dB (95% CI 6.92 to 10.25 dB) compared to no instruction, making education critical for effectiveness. 3
• There is no significant difference in hearing loss prevention between earmuffs and earplugs at long-term follow-up, so choice can be based on comfort and compliance. 3
• More frequent use of hearing protection devices as part of comprehensive programs reduces hearing loss risk (OR 0.40,95% CI 0.23 to 0.69), though this is very low-quality evidence. 3

Early Detection: Catching Damage Before It's Too Late

Mandatory Audiometric Surveillance

• Annual pure-tone audiometry testing at 3,4, and 6 kHz is mandatory for all workers exposed to occupational noise exceeding permissible levels, as these frequencies reveal the earliest permanent changes. 2, 4
• The classic audiometric notch typically centers at 3-6 kHz, with 4 kHz being the most characteristic frequency affected in noise-induced hearing loss. 4

Critical Pitfall to Avoid

• Do not wait for permanent threshold shifts before implementing aggressive intervention - temporary threshold shifts (TTS) can indicate irreversible neural damage even when hearing thresholds eventually return to normal. 2, 4
• This "hidden hearing loss" involves loss of synaptic connections between inner hair cells and auditory nerve terminals, causing functional deficits in speech understanding in noisy environments despite normal audiograms. 2, 4
• 5-15% of adults seeking audiologic help have normal hearing thresholds but may have hidden hearing loss from noise-induced cochlear synaptopathy. 2, 4
• Consider monitoring for temporary threshold shifts after work shifts as a promising approach to detect damage before permanent hearing loss occurs. 2, 4

Treatment of Established Hearing Loss and Associated Tinnitus

For Hearing Loss

• Hearing aids should be evaluated for patients with hearing loss and persistent tinnitus, even if the hearing loss is mild or unilateral. 2
• Comprehensive audiologic examination is essential, especially for unilateral or persistent tinnitus. 2

For Associated Tinnitus (Common Comorbidity)

• Cognitive Behavioral Therapy (CBT) is strongly recommended for patients with persistent, bothersome tinnitus - this is the only treatment modality with strong evidence. 2
• Education and counseling about tinnitus management strategies should be provided to all patients. 2
• Prompt identification and intervention is required for patients with tinnitus accompanied by severe anxiety or depression due to increased suicide risk. 2, 5

What NOT to Do for Tinnitus

• Medical therapy including antidepressants, anticonvulsants, and anxiolytics is not recommended specifically for treating persistent tinnitus. 2
• Dietary supplements such as Ginkgo biloba, melatonin, or zinc are not recommended for tinnitus treatment. 2
• Transcranial Magnetic Stimulation (TMS) and intratympanic medications should not be used for routine tinnitus treatment. 2

Hearing Loss Prevention Programs: Mixed Evidence

• Comprehensive hearing loss prevention programs (HLPPs) that include training, education, and engineering controls show inconsistent results, with some studies showing workers in HLPPs had 1.8 dB greater hearing loss at 4 kHz than non-exposed workers. 3
• The most effective component of HLPPs appears to be consistent use of hearing protection devices rather than other program elements like training alone. 3
• On-site training sessions without emphasis on hearing protection compliance did not reduce personal noise exposure levels compared to information only (MD 0.14 dB; 95% CI -2.66 to 2.38). 3

Key Clinical Pitfalls

• Focusing only on audiometric thresholds while missing functional deficits in speech understanding - hidden hearing loss can cause significant disability without detectable threshold changes. 2
• Delaying referral to audiologists for comprehensive evaluation when symptoms first appear. 2
• Assuming that normal audiometry means no noise damage has occurred - cochlear synaptopathy can occur with moderate noise exposure resulting in only temporary threshold shifts. 2