Hearing loss is a common condition that affects millions of Americans every year. One of the main culprits of hearing loss is aging, a process that happens slowly over many years.
Noise-induced hearing loss is much different.
One condition that stands out is acoustic trauma, hearing loss caused by exposure to loud noise.
This condition doesn’t need years to affect you — it can happen instantly after sudden exposure to loud noise.
This article gives you everything you need to know about acoustic trauma, including some signs and symptoms to watch out for to help you determine if it is affecting you.
What Is Acoustic Trauma?
In simple terms, acoustic trauma is an injury to the eardrum resulting from loud noise exposure. Typically, this is a result of short-duration exposures.
Examples may include exposure to gunshots, explosions, or machinery. This would be acute acoustic trauma.
Acoustic trauma can also happen from continued exposure to loud noises.
Those at risk for chronic acoustic trauma could include those working in construction or factory-type settings who constantly experience loud machinery.
One demographic at a higher risk for acoustic trauma sometimes referred to as aural blast injury, is military personnel.
In fact, according to Military Medicine (MilMed), acoustic trauma-induced hearing and tinnitus are the two most common disabilities that military veterans face.
It has a 13 to 18 percent annual rate among veterans.
Oddly enough, exposure to loud sounds isn’t the only way to induce acoustic trauma.
Even quieter high-frequency sounds can damage frequency receptors, inner hair cells, and outer hair cells. The normal frequency range for humans is 20 Hz to 20 kHz.
What Are the Symptoms of Acoustic Trauma?
In most cases, acoustic trauma causes some degree of hearing loss.
The severity of the hearing loss can vary, from mild to severe hearing loss. This is often referred to as noise-induced hearing loss.
Noise-Induced Hearing Loss
Hearing loss happens when your auditory system is damaged.
This can happen over many years as a result of normal aging. Age is the strongest predictor of hearing loss among adults aged 20 to 69.
While age-related hearing loss is the most common form, noise-induced hearing loss (NIHL) is a close second. It can happen to anyone at any stage of life.
According to the National Institute on Deafness and Other Communication Disorders (NIDCD), as many as 24 percent of adults have noise-induced hearing loss in one or both ears — roughly 40 million people.
They also estimate that nearly 17 percent of teenagers (ages 12 to 17) may also show signs of NIHL.
Sensorineural hearing loss
Both age-related hearing loss and NIHL are considered a form of sensorineural hearing loss (SNHL). This occurs as a result of damage to the inner ear.
The inner ear comprises fluid-filled chambers and semicircular canals. It receives sound vibrations from the ear canal and middle ear, transmitting them as electrical impulses to the brain through our auditory nerve. It houses important vestibular and auditory components like the cochlea and hair cells.
This SNHL can be temporary or more permanent — requiring amplification devices like hearing aids or cochlear implants. In the case of acoustic trauma, sudden sensorineural hearing loss is also possible. It is considered a medical emergency.
According to the American Academy of Otolaryngologist-Head and Neck Surgery, sudden sensorineural hearing loss affects around five to 27 per 100,000 annually in the United States.
Common signs of hearing loss may include:
- Increased difficulty hearing speech over the phone.
- Sounds and speech may sound muffled or far away.
- A constant need to turn up the volume on the TV, radio, and other devices.
- You must read lips to understand what people are saying to you.
- Difficulty determining where sounds are originating.
- Difficulty hearing speech in noisy environments.
Aside from hearing loss, other common symptoms of acoustic trauma can include tinnitus (ringing in the ear), a feeling of fullness in the ears (aural fullness), recruitment (ear pain associated with loud noise), hyperacusis (hypersensitivity to loud sound), and vertigo.
What Causes Acoustic Trauma?
Acoustic trauma results from injury or damage to the inner ear. Sound is measured in decibel (dB) units. In terms of sound, the threshold of hearing in decibels is as follows:
- 0 to 30 dB are considered faint
- 40 to 60 dB are considered quiet to moderate
- 70 to 90 are very noisy
- 100 to 120 are painful
According to the CDC, decibels ratings for common sounds include:
- Whispering – 30 dB
- Normal conversation – 60 dB
- City traffic – 80 to 85 dB
- Motorcycles – 95 dB or more
- Shouting in the ear – 110 dB
- Emergency sirens – Around 120 dB
- Gunshots and fireworks – 140 to 160 dB
Regarding hearing thresholds, decibels above 130 are considered intolerable and can cause hearing impairment and loss within minutes.
Chronic exposure to sounds as low as 85 dB can contribute to permanent hearing loss. This is also known as permanent threshold shift (PCS).
Acoustic trauma occurs when noise levels exceed these normal decibel ranges.
As stated above, this could include exposure to gunshots, explosions, and loud machinery.
In some cases, sudden exposure to noise in intolerable decibel ranges could rupture the tympanic membrane of the ears. The prevalence of this condition is high among military personnel.
However, even regular activities that contribute to loud noise, like mowing the lawn or listening to loud music with headphones, can contribute to acoustic trauma and noise-induced hearing loss.
How To Identify Acoustic Trauma
If you think you’ve experienced acoustic trauma and show associated signs of hearing loss, the best thing to do is consult a healthcare professional.
While a primary care physician can offer insight into hearing loss, they may refer you to an otologic professional specializing in ear disorders and hearing loss. This may be an audiologist or otolaryngologist (ear, nose, and throat physician).
These healthcare professionals will most likely perform:
- A physical examination of the ears, checking the external and internal ear canal for trauma or abnormalities. They will also check for other abnormalities around the head and neck areas.
- A detailed medical history will also be obtained. This will be specific to hearing loss and the events surrounding and preceeding it.
- Audiometry (hearing test) will be used to check for and diagnose hearing loss. These will test your ability to hear sound intensity and frequencies. Also, the provider may do behavioral tests like pure tone audiometry to test hearing sensitivity.
Hearing health professionals like audiologists are trained to diagnose hearing loss, interpret data from audiograms, and can provide advice on follow-up treatments.
How Is Acoustic Trauma Treated?
Treatment for acoustic trauma varies depending on the cause and severity of symptoms.
For example, long-term exposure to loud noise that causes permanent noise-induced hearing loss may require amplification devices like hearing aids.
Unfortunately, acoustic trauma is not a condition that can be reversed. The main goal of treatment is to prevent further damage and salvage the remaining hearing.
Some common treatment options for acoustic hearing loss include:
- Eardrum repair – If a sudden loud noise causes a rupture of the tympanic membrane, surgical eardrum repair may be the only option.
- Corticosteroid injections – Steroid treatment, specifically intratympanic steroid injections, are a common treatment option to reduce inflammation in the middle ear. The earlier the treatment is done, the better the outcome.
- Hyperbaric oxygen therapy – In extreme cases, procedures like hyperbaric oxygen therapy are used. In short, this procedure restores adequate oxygen supply to inner ear components such as the cochlea. Cochlear hypoxia is common during acute acoustic trauma events.
Prevention of Acoustic Trauma
In many cases, acoustic trauma and noise-induced hearing loss are preventable. Practicing good hearing health and protecting yourself from exposure to hazardous noise is extremely important.
Here are some tips:
- Educate yourself and your loved ones about the types of noise and sounds contributing to acoustic trauma and noise-induced hearing loss.
- Wear protective hearing equipment, like earplugs or over-the-head earmuffs, to help protect yourself during loud activities. These are inexpensive.
- If hearing equipment is not an option, moving away from the source of the loud noise may be the only option. Limiting the time of exposure is crucial.
Conclusion
Acoustic trauma occurs due to sudden or long-term exposure to loud sounds. In many cases, hearing loss is an associated symptom.
Thankfully, there are treatment options, but prevention remains the safest bet. If you think acoustic trauma has affected you, consult a hearing health professional as soon as possible.
Looking for more information about hearing loss and possible treatments? Explore the USA Rx Hearing Loss Information Hub for more articles like this.
References, Studies and Sources:
Aural Blast Injury/Acoustic Trauma and Hearing Loss | Military Medicine | Oxford Academic
Noise-Induced Hearing Loss (NIHL) | NIDCD | PubMed