Tinnitus can be classified into two main types called objective and subjective tinnitus
. Objective tinnitus is defined by sounds generated in the body and then transmitted to the ear. Subjective tinnitus is caused by abnormal activity in the nervous system. Objective tinnitus is a rare condition. However, subjective tinnitus is frequently suffered with varying severity in individuals. The characteristics of the subjective tinnitus can differ, the volume of the tinnitus can be barely noticeable, slightly annoying or it can severely reduce the quality of life by affecting concentration, disrupting sleep and tinnitus can even lead to suicide. At present there are no tests to measure the severity of subjective tinnitus, it is a personal experience and only the person who suffers the tinnitus can assess how much it is impacting them.
Research has demonstrated that the amount of people affected by subjective tinnitus increases with age. Between 20-30 years of age approximately 5% of people are affected whereas in the above 50 year old age group it increases to approximately 12% of people. There is variability in these statistics from study to study. Usually very troublesome tinnitus is rare at a young age but once again increases with age to about 13% for individuals older than 65 years. Factors that can increase the chance of tinnitus include hearing loss. Tinnitus can also happen after being exposed to a loud noises, using toxic antibiotics, infectious diseases and direct trauma to the nerves related to hearing.
It has been agreed that subjective tinnitus is not a disease but merely a symptom. All the different types of tinnitus probably have a different mechanism that results in the tinnitus. Up until recently the belief was held that tinnitus could only be caused by the ear and any problem with functioning that may result in tinnitus could only be found in the ear. However science has no found that most types of tinnitus are a result from problems with the nervous system and usually the result of the nervous system changing or adapting in an abnormal way.