What is Tinnitus?
Tinnitus is commonly known as “ringing of the ears”: it is a condition in which the brain hears phantom sounds without the stimulus of an external noise source. The sound may appear as a whoosh, whistle, or pop, in addition to ringing.
Ninety-percent of tinnitus cases accompany some degree of hearing loss. Tinnitus affects approximately 50 million Americans, while 60% of veterans returning from Afghanistan and Iraq report cases of tinnitus and hearing loss.
There are two types of tinnitus: objective and subjective. Objective tinnitus can be heard by the person who has the condition, as well as by people in close proximity. Subjective tinnitus can only be heard by the person with tinnitus. Though there is no singular cause for tinnitus, it is believed that tinnitus occurs after exposure to dangerous levels of sound over a lengthy period of time or after a short traumatic burst of sound, such as gunfire or an explosion. Another cause is certain classes of medications, such as aminoglycoside antibiotics.
Tinnitus may appear infrequently or be a permanent fixture in a person’s day, from morning to night. Tinnitus has been linked to an increased risk of depression, stress, and anxiety.
2014 Brain Research Study Revelations
In 2014, Fatima Husain, a professor of speech and hearing science at the University of Illinois, headed a study to explore the link between tinnitus and depression, stress, and anxiety. Using MRI brain scans, Husain and her team tested the response time of three distinct subject groups: people with mild to moderate hearing loss and mild tinnitus, people with mild to moderate hearing loss without tinnitus, and people of the same age group without tinnitus or hearing loss.
Husain’s team played three sets of sounds: pleasant, unpleasant, and emotionally neutral, each set comprising 30 sounds (such as a baby laughing, a woman screaming, and a water bottle opening). Subjects of the study were asked to indicate the emotional response to each sound – pleasant, unpleasant, or neutral.
From this study, Husain’s team found that subjects with tinnitus responded more slowly to each sound, compared to subjects with normal hearing. Husain and team found that activity in the amygdala (the part of the brain that processes emotions) was lower in people with tinnitus and hearing loss.
Husain says, “We thought that because people with tinnitus constantly hear a bothersome, unpleasant stimulus, they would have an even higher amount of activity in the amygdala when hearing these sounds, but it was lesser…because they’ve had to adjust to the sound, some plasticity in the brain has occurred. They have had to reduce this amygdala activity and reroute it to other parts of the brain because the amygdala cannot be active all the time due to this annoying sound.” Husain plans to continue her research to improve the quality of life for people who suffer from tinnitus, especially veterans.