Tinnitus is the perception of sound when no actual external noise is present. While it is commonly referred to as “ringing in the ears,” tinnitus can manifest many different perceptions of sound, including buzzing, hissing, whistling, swooshing, and clicking. In some rare cases, tinnitus patients report hearing music. Tinnitus can be both an acute (temporary) condition or a chronic (ongoing) health malady.
The important thing to remember about tinnitus is that the brain’s response to these random electrical signals determines whether or not a person is annoyed by their tinnitus or not. Magnetoencephalography (MEG, for short) studies have been used to study tinnitus and the brain. MEG takes advantage of the fact that every time neurons send each other signals, their electric current creates a tiny magnetic field. MEG allows scientists to detect such changing patterns of activity in the brain 100 times per second. These studies indicated tinnitus affects the entire brain and helps with understanding why certain therapies are more effective than others.
Other potential sources of the sounds normally associated with tinnitus should be ruled out. For instance, two recognized sources of high-pitched sounds might be electromagnetic fields common in modern wiring and various sound signal transmissions. A common and often misdiagnosed condition that mimics tinnitus is radio frequency (RF) hearing, in which subjects have been tested and found to hear high-pitched transmission frequencies that sound similar to tinnitus.
Persistent tinnitus may cause anxiety and depression. Tinnitus annoyance is more strongly associated with psychological condition than loudness or frequency range. Psychological problems such as depression, anxiety, sleep disturbances and concentration difficulties are common in those with strongly annoying tinnitus. 45% of people with tinnitus have an anxiety disorder at some time in their life.
Individuals with tinnitus describe perceiving a wide variety of sounds including ringing, clicking, hissing, humming, chirping, buzzing, whistling, whooshing, roaring, and/or whirling. These sounds may be present at all times, or they may come and go. The volume, pitch or quality of tinnitus sounds can fluctuate as well. Some people report that their tinnitus is most obvious when outside sounds are low (i.e. during the night). Other individuals describe their tinnitus as loud even in the presence of external sounds or noise, and some describe it as exacerbated by sounds. Tinnitus can affect one ear or both ears. It can also sound like it is inside the head and not in the ears at all.
It is also very common for jaw opening to change the loudness or frequency of tinnitus. This is likely a variant of somatic modulation of tinnitus (see above). The sensory input from the jaw evidently interacts with hearing pathways. The muscles that open the jaw are innervated by the same nerve, the motor branch of 5, that controls the tensor tympani in the ear. In other words, changing tension in the jaw may also change muscle tension in the ear.
A common cause of tinnitus is inner ear hair cell damage. Tiny, delicate hairs in your inner ear move in relation to the pressure of sound waves. This triggers cells to release an electrical signal through a nerve from your ear (auditory nerve) to your brain. Your brain interprets these signals as sound. If the hairs inside your inner ear are bent or broken, they can "leak" random electrical impulses to your brain, causing tinnitus.