Scientists know that tinnitus, or ringing in the ears, is associated with hearing loss, aging, head and neck injuries, and exposure to loud noises. However, what actually happens in the body to cause it is less understood.
The new study was published Thursday in the journal scientific report supports the theory that the root cause of tinnitus may be similar to phantom limb syndrome, where people feel pain in the limbs they no longer have.
“That means I lost my hearing, and my brain no longer receives auditory information,” says study lead author Stéphane Maison, a clinical audiologist at Mass Eye & Ear in Boston. . The brain then becomes more active to compensate for the hearing loss, “so you start hearing noises that aren’t there,” he says.
Maison says this understanding of tinnitus has received pushback from the scientific community because it assumes that tinnitus patients already have hearing loss. However, many people with tinnitus can still function normally during commonly performed hearing tests, he said. Such an assessment, called a pure tone test, often requires patients to raise their hands when they hear a beep to measure the quietest sound that can be detected at various pitches.
Maison said the findings show that the pure tone test assesses nerves that are more sensitive to softer sounds. It does not take into account “hidden” hearing loss caused by damage to the auditory nerve in the inner ear, which is sensitive to loud sounds.
“We know that hearing tests don’t tell the whole story,” Maison said.
The study involved 294 participants between the ages of 18 and 72, all of whom performed normally on the pure tone test. Participants were divided into three groups: 201 adults who had never experienced tinnitus, 64 adults who had experienced episodic tinnitus, and adults who had experienced persistent tinnitus for at least 6 months. 29 people.
The researchers conducted a hearing loss test by placing electrodes in the participants’ ear canals and scalps to measure auditory nerve and brain activity in the inner ear in response to clicks.
The results showed that participants with tinnitus had much less activity in the auditory nerve and increased activity in the brainstem compared to participants with “normal hearing,” Maison said. This suggests that tinnitus patients may have damaged auditory nerves that no longer send signals to the brain, potentially resulting in brain activity that causes the patient to hear ringing, buzzing, or hissing sounds. He said it could be cause for hearing.
Studies show that as many as 15% of adults worldwide suffer from tinnitus.
“Everything that is being done to better understand the causes of tinnitus is an important step toward a cure,” Maison said.
Audiologist Laura Herman of the Johns Hopkins School of Medicine in Baltimore, who was not involved in the study, said the comparison to phantom limb syndrome is apt.
He noted that the study outlines another way to measure the “hidden hearing loss” in the auditory nerve associated with tinnitus. She said the test that can be performed at a hearing clinic is called electrocochleography, which is another test that similarly evaluates the inner ear’s response to sound.
“I thought this was really interesting because a lot of audiologists have the equipment to do it,” Herman said. “So this could be a really great way to validate people’s complaints that come in.”
Research shows that people who suffer from debilitating tinnitus have trouble sleeping and feel anxious and depressed.
Although there is no cure for tinnitus, there are simple steps people can take to protect themselves and potentially prevent the condition, says Aniruddha Deshpande, dean of the Department of Speech and Hearing Sciences at Hofstra University in New York. He said that there is.
“Anything that can cause hearing loss can actually cause tinnitus, because the underlying pathophysiology may be similar,” Deshpande says. “So common sense precautions to prevent exposure to loud noises are something we can all do.”
Deshpande said the most common cause of hearing loss these days is listening to music at high volume through headphones or speakers. Deshpande said more research is needed to establish an “objective” threshold for what is considered safe, but previously research suggests You should listen to music at a volume no higher than 50% of your phone’s maximum volume.
For example, in environments where you can’t control the sounds around you, such as at a concert, wearing earplugs or muffs can help prevent damage, he said.
