|Your Guide to Tinnitus (Ringing in the ears)
NVRC Note: The Better Hearing Institute now has Your Guide to Tinnitus by Richard Tyler, PhD of the University of Iowa. Below you’ll find an excerpt from the article. You can get a PDF of Your Guide to Tinnitus at http://www.betterhearing.org/request_information.cfm or read the full article at http://www.betterhearing.org/tinnitus/BHI_Guide_to_Tinnitus.cfm
Tinnitus is the perception of a sound that has no external source. Some of the more common sounds reported are: ringing, humming, buzzing, and cricket-like.
It can also be a combination of sounds, and for many, the sound of their tinnitus actually changes. It can be constant or intermittent and is heard in one ear, both ears or in the head. Tinnitus can originate in the middle ear (behind the eardrum) or in the sensorineural auditory system. Occasionally people with tinnitus hear music or singing. This is different from someone who has a mental illness and is experiencing hallucinations. Tinnitus is not a 'phantom sound'. There is real neural activity in your brain that you are hearing as your tinnitus.
There are many causes of tinnitus, and often the cause is unknown. Just about anything that can cause hearing loss can also cause tinnitus. The most common causes are: Noise exposure (e.g. from shooting or machines at work), a natural part of the aging process, head injury (e.g. from a car accident or fall), as a side effect of medications (e.g. aspirin).
Tinnitus is almost always accompanied by hearing loss. If you have tinnitus, you should have your hearing tested by a hearing health professional. Some 30 million adults suffer from persistent tinnitus (it can also affect children). For 12 million, the problem is severe enough that it impacts their everyday life. Because tinnitus can be a symptom of a more serious disorder, it is important to have an appropriate health evaluation.
Nearly four in ten people experience tinnitus 80% of the time during a typical day; slightly more than one in four people describe their tinnitus as loud; and about one in five describe their tinnitus as disabling or nearly disabling. Tinnitus is sometimes accompanied by hyperacusis (when moderately loud sounds are perceived as very loud).
Traditionally, many classify tinnitus as either being: Objective (it can be heard by the examiner), or subjective (it can only be heard by the person with tinnitus). But this is not always helpful because in many people with tinnitus an objective sound is emitted from the cochlea in the inner ear, which is unrelated to tinnitus in most cases. Therefore, I have suggested that tinnitus be referred to as either middle ear tinnitus, or sensorineural tinnitus. This categorizes tinnitus in the same way hearing loss is categorized, and is helpful in understanding its mechanism and treatments.
Middle ear tinnitus originates in the cavity behind your eardrum (less common). Of course, we would like to determine whether tinnitus originates in the cochlea, the neural pathways, or the brain. At present, this is not possible. It is likely that in most circumstances, tinnitus originates in the cochlear (with a noise induced hearing loss). But it might also originate in the brain stem or the brain (often with a hit to the skull). Wherever the tinnitus originates, it must be interpreted by the auditory part of the brain. Some people mistakenly suggest that it is a relatively new idea that tinnitus might be coded in the brain, but in fact this was suggested decades ago.
Middle ear tinnitus is either a result of abnormal blood flow or muscles twitching. Sometimes the tinnitus might sound like a pulsing or throbbing, or like a twitching. Often the tinnitus is only in one ear. In some of these situations, the tinnitus can be treated surgically, and thus a visit to an otologist (a physician specializing in the ear) is advisable.
Sensorineural tinnitus can have many causes (e.g. noise, medications, head injury, infections, and aging). Something is establishing abnormal spontaneous nerve activity. As represented in the brain, this might be an increase in activity, synchronous activity across nerve fibers, or an over-representation of some frequency region (or combinations of the above three).