Acoustic trauma is an injury to the inner ear that’s often caused by exposure to a high-decibel noise. This injury can occur after exposure to a single, very loud noise or from exposure to noises at significant decibels over a longer period of time.
Some injuries to the head can cause acoustic trauma if the eardrum is ruptured or if other injuries to the inner ear occur.
The eardrum protects the middle ear and inner ear. It also transmits signals to the brain by way of small vibrations.
Acoustic trauma can damage the way that these vibrations are handled, resulting in hearing loss. Sound moving into the inner ear can cause what doctors sometimes call a threshold shift, which can trigger hearing loss.
If your doctor believes that your symptoms indicate acoustic trauma, they may try to differentiate between trauma that occurred suddenly through injury and trauma that occurred through ongoing exposure to loud noises.
Different degrees of acoustic trauma can require different treatments.
People at an increased risk for acoustic trauma include those who:
- work at a job where loud industrial equipment operates for long periods of time
- live or work where other high-decibel sounds continue for long periods of time
- frequently attend music concerts and other events with high-decibel music
- use gun ranges
- encounter extremely loud sounds without proper equipment, such as earplugs
People continually exposed to noise levels over 85 decibels are at an increased risk for acoustic trauma.
Your doctor may provide an estimate of the decibel range of normal daily sounds, like an estimate of around 90 decibels for a small engine. They’ll do this to help you assess whether the sounds that you encounter put you at a higher risk for acoustic trauma and hearing loss.
Under 70 decibels or less is considered safe for ongoing listening. This is the estimated noise level of an average group conversation.
Three important factors have a role in acoustic trauma. These include:
- the intensity of sound measured in decibels
- the pitch or frequency of the sound (higher frequencies are more damaging)
- the total time the person was exposed to the sound
The main symptom of acoustic trauma is hearing loss.
Injury occurs at the level of the inner ear. The sensitive hair cells can lose their connections to the nerve cells responsible for hearing.
Ear structures may also be directly damaged by loud noise. Sudden sounds above 130 decibels can damage the ear’s natural microphone, the organ of Corti.
Acoustic injury can injure the eardrum, along with the small muscles in the ear, particularly the tensor tympani muscle.
In many cases of long-term sound damage, people first begin to have difficulty hearing high-frequency sounds. Difficulty hearing sounds at lower frequencies may occur later.
Your doctor may test your response to different frequencies of sound to assess the extent of acoustic trauma.
One of the most important symptoms that can signal the onset of acoustic trauma is called tinnitus. Tinnitus is a type of injury to the ear that causes a buzzing or ringing sound.
Those with mild to moderate tinnitus will most often be aware of this symptom when they’re in silent environments.
Tinnitus can be caused by drug use, changes to blood vessels, or other conditions and factors, but it’s often a precursor to acoustic trauma when it’s caused by exposure to loud noises.
Tinnitus can be persistent or chronic. Long-term tinnitus is a good reason to suspect acoustic trauma.
Your doctor will ask you what kind of noises you’ve been exposed to during different times of your life to help make a diagnosis.
They may also use something called audiometry to detect signs of acoustic trauma. In this test, you’re exposed to sounds of varying loudness and of different tones to more carefully assess what you can and can’t hear.
Technological hearing assistance
Hearing loss can be treated, but it can’t be cured.
Your doctor may recommend technological assistance for your hearing loss condition, such as a hearing aid. New types of hearing aids called cochlear implants may also be available to help you deal with hearing loss from acoustic trauma.
Your doctor will most likely recommend using earplugs and other kinds of devices to protect your hearing.
These items are part of the personal protective equipment (PPE) that employers should offer to people when they’re in a workplace with exposure to loud noises.
Your doctor may prescribe oral steroid medications to help with some cases of acute acoustic trauma.
However, if you’re experiencing hearing loss, your doctor will stress noise protection of the ear and limit exposure to loud environments to prevent the problem from getting worse.
Acoustic trauma and related hearing loss cannot be reversed.
Protecting your ears from loud noises and limiting excessively loud experiences can help you maintain your hearing. An ear specialist can help determine the treatment options that are best for you.