'What Did You Say?' Hearing Loss and Brain Injuries

It’s no surprise that some symptoms of traumatic brain injury (TBI) include headaches and memory problems. But hearing loss may also accompany a TBI, either because the injury damages the ear or because there is damage to the part of the brain that processes sound. In addition, loud noises that might just be irritating to people without a brain injury can cause problems such as headaches and fatigue for those with a TBI.

Research continues to fully understand the mechanisms associated with hearing loss and auditory and vestibular (important part of the ear for balance) system injuries in individuals with TBI, said Katie Stout, director of clinical affairs for Defense and Veterans Brain Injury Center. In the meantime, there are specialty treatments and rehabilitation strategies available for hearing and balance challenges in individuals with TBI.

Managing Loud Noise

Becoming aware of how your surroundings can affect your hearing is a key factor in managing hearing problems associated with TBI, according to experts from the Defense Department Hearing Center of Excellence (HCE).

“Any sound above 85 decibels has the potential to damage the auditory system. However, the amount of damage is dependent on the loudness and duration of the sound,” said Dr. Lynn Henselman, HCE interim director and audiologist. By way of comparison, a kitchen blender is about 88 decibels.

Because service members in particular are often exposed to high noise levels, hearing protection is crucial, especially with a TBI, said Dr. Jeremy Nelson, HCE science advisor and neuroscientist.

“What makes patients with a TBI unique is that they come with other factors we need to consider when protecting them,” said Nelson. In general, however, standard hearing protection might mitigate some TBI symptoms.

A person should only be exposed to an average of 85 decibels of sounds over the course of an eight-hour day, said Lt. Col. Andy Merkley, Army audiology liaison to HCE.

Sample decibel measures of common sounds include:

• 60 decibels: conversation, dishwasher or clothes dryer
• 70 decibels: busy traffic, vacuum cleaner, alarm clock
• 80 decibels: garbage disposal, dishwasher

Every time the noise level increases by three decibels, the length of safe listening time is cut in half, Merkley said. An 88-decibel sound should only be listened to for four hours; a 91-decibel sound, for two hours.

A simple way to determine whether a noise is too loud is the “three-foot rule,” which means that if you have to raise your voice in order for someone standing within three feet of you to hear you over other noise, your hearing is at risk, Merkley said.

Events such as air shows can be hard on anyone’s hearing regardless of whether they have a TBI. A jet flying overhead can be around 119 decibels, Merkley said.