Noise-induced hearing loss

**Impact of Noise-Induced Hearing Loss (NIHL) on Quality of Life:**
– Difficulty hearing in noisy environments
– Loss of audibility and clarity in speech perception
– Consonants like s and t are challenging to hear
– Unilateral hearing loss affects sound localization
– NIHL affects quality of life beyond hearing symptoms
– Disability-adjusted life years (DALYs) measure the impact of hearing loss
– NIOSH reported 2.5 healthy years lost per 1,000 noise-exposed U.S. workers annually
– Mining, Construction, and Manufacturing workers lose the most healthy years
– NIHL impacts daily activities and social interactions
– NIHL affects communication and social interactions
– Challenges in social interactions can lead to decreased self-esteem
– Social isolation can result from hearing loss
– Hearing impairment may lead to depression, especially with tinnitus
– Hearing loss limits the benefits of sound on quality of life

**Types and Symptoms of Noise-Induced Hearing Loss (NIHL):**
– Temporary and Permanent Hearing Changes
– PTS is a permanent change in hearing threshold
– TTS is a temporary change in hearing threshold
– External symptoms of acoustic trauma include tinnitus and otalgia
– Hyperacusis and dizziness can also occur
– PTS and TTS are measured in decibels
– Tinnitus
– Tinnitus is hearing sound without an external source
– NIHL can cause high-pitched tinnitus
– About 50 million Americans have tinnitus
– Tinnitus is a major cause of disability claims in the military
– Tinnitus can be exacerbated by post-traumatic stress disorder

**Causes and Prevention of Noise-Induced Hearing Loss (NIHL):**
– Cause
– Exposure to sound over 85dB(A) can cause permanent hearing loss
– Two types of NIHL: acoustic trauma and gradual development
– Acute acoustic trauma results from one-time exposure to excessive sound
– Gradual NIHL occurs from repeated exposure to loud sounds
– Earplugs recommended for loud environments like concerts
– Personal Listening Devices
– Increased exposure to loud noise is a risk for hearing loss
– Over half of adolescents exposed to loud music through devices
– Strong correlation between extended device usage and hearing loss
– Research on personal listening devices and hearing loss is limited
– Extended duration of device usage linked to hearing loss
– Video Game Sound Levels
– Studies show association between gaming and hearing loss
– Average sound levels during gameplay exceed permissible levels
– Video game sound levels can lead to hearing loss or tinnitus
– Research published in BMJ Public Health on gaming and hearing loss
– Subjects playing games for 3 hours per week had high sound exposure
– Prevention
– NIHL can be prevented through personal noise reduction tools like ear protection
– Education and hearing conservation programs are essential in preventing NIHL
– Simple steps like turning down volume, moving away from noise sources, and wearing protectors can prevent NIHL
– Non-occupational noise exposure prevention relies heavily on public awareness campaigns
– Nearly half of hearing loss cases could be prevented through primary prevention efforts

**Mechanisms of Noise-Induced Hearing Loss (NIHL) and Physiological Response:**
– Noise-induced hearing loss mechanisms
– Sound transmission pathway from source to brain
– NIHL due to excessive sound intensity
– Biological mechanisms of NIHL
– Sensitivity of hair cells to different frequencies
– Damaged sensory hairs (stereocilia) of hair cells lead to permanent hearing loss
– Inflammation causes poor blood flow and oxygen supply, worsening hair cell degeneration
– Excitotoxicity from noise overstimulation can cause synaptic damages
– Noise exposure can lead to excessive release of glutamate, causing synaptic damages
– Hearing loss caused by wiring damage can be recovered within 2-3 days

**Prevention Strategies, Diagnosis, and Individual Susceptibility to Noise-Induced Hearing Loss (NIHL):**
– Diagnosis
– NIHL often presents with a notch-shaped high frequency hearing loss in audiograms
– Hearing sensitivity in higher frequencies, especially at 4000Hz, can decrease
– Symptoms of NIHL are typically present in both ears equally
– Variations in audiological results can occur based on ear canal resonance and exposure length
– Harmful noise exposure can broaden affected frequencies and worsen severity
– Individual Susceptibility towards Noise
– Factors like missing acoustic reflex and previous hearing loss can increase susceptibility to NIHL
– Bad general health state, including cardiovascular issues, can contribute to NIHL
– Cigarette smoking and exposure to ototoxic chemicals can increase vulnerability to NIHL
– Type 2 diabetes has been implicated in individual susceptibility to NIHL
– High blood viscosity and other health conditions can make individuals more prone to NIHL
– Personal noise reduction devices
– Passive ear protection includes earplugs or earmuffs
– Earplugs and earmuffs can provide 10dB to 40dB of attenuation
– Cochrane review found that training of earplug insertion can reduce noise exposure
– Custom-molded earplugs offer higher consistency of performance
– Active ear protection electronically filters out noises
– Hearing conservation programs
– Workers exposed to noise levels above 85 dBA require a hearing conservation program
– OSHA mandates noise measurement, control, audiometric testing, protection, education, and record-keeping
– Some states have adopted different standards for hearing conservation
– HCPs aim to change behavior towards risk and severity of hearing loss
– Stricter legislation might reduce noise levels