Definition of Acoustic trauma:
Acoustic trauma is injury to the hearing mechanisms in the inner ear due to very loud noise.
What are the causes and risks of the condition?
Most cases of occupational hearing loss develop gradually. Common environmental factors that contribute to hearing loss include the following:
# harmful gases, such as carbon monoxide
# a loud, intense burst of sound, such as a gunshot
# loud noise over a long period of time
# metals, such as lead, arsenic, manganese, and mercury
# solvents, such as toluene and other chemicals used in manufacturing
Individuals who are exposed to noise along with one of the other environmental factors may experience more significant hearing loss.
Symptoms & Signs of Acoustic Trauma
The person with occupational hearing loss may have a feeling of fullness in the ears. Sounds may seem muffled. He or she cannot hear very well, especially at high frequencies. There is usually a high-frequency ringing in the ears.
Most people recover their hearing completely within 24 to 48 hours. However, even when hearing returns, hair cells are permanently damaged. People who are exposed to noise repeatedly over a long time will have those noise injuries build up. The result is a hearing loss at high frequencies that slowly gets worse. These people may not even be aware that anything is wrong with their hearing.
Some sounds are so loud that high-frequency hearing is immediately and permanently lost. Examples include explosions, artillery fire, fireworks, and gunshots. Some people seem to be more prone to injury from noise exposure. The same noise that causes hearing loss in them may present no difficulty for others. Hearing that does not return after an acute noise injury is called a permanent threshold shift.
How is the condition diagnosed?
Diagnosis of occupational hearing loss begins with a medical history and physical exam. The healthcare provider may order the following tests:
# an otoacoustic emissions test, which measures how well the hair cells are working
# a standard hearing test
# an X-ray of the head or a cranial CT scan to detect underlying problems
Acoustic Trauma Treatment
What are the treatments for the condition?
Treatments for occupational hearing loss include the following:
# aural rehabilitation, which teaches the individual how to work with hearing loss
# hearing aids
# protective equipment to reduce further hearing damage
# workplace redesign to minimize further hearing loss
What are the side effects of the treatments?
There are no side effects from the treatment options listed.
What happens after treatment for the condition?
Many people with hearing aids have a hard time communicating when there is a lot of background noise. Other people should be encouraged to speak into the less-impaired ear of the person. Gestures and facial expressions can also help, when used appropriately. The person may need assistance dealing with adjustment to hearing loss. He or she may have emotional reactions such as anger, frustration, and loneliness.
How is the condition monitored?
The healthcare provider may order periodic hearing tests to detect further hearing loss. Any new or worsening symptoms should be reported to the healthcare provider.
Author: Mark Loury, MD
Editor: Jonas Linh