Tinnitus is the perception of sound in the absence of sound. That is, intermittent or constant ringing, buzzing, hissing, or beating sound when there is no such sound.
How the ear works:
We have to understand how the ear works in order to understand what causes tinnitus, and eventually how to cure it. The ear is a complex organ that converts sound-waves into brain signals by passing the waves through the ear canal, onto the ear drum. Consequently, the waves then pass through the ear bones into the cochlea, that picks up individual frequencies of sound.
The brain and cochlea are arranged in exactly the same way. That is, the pitches that are next to each other on the cochlea being exactly next to each other in the brain as well. Accordingly, the cochlea transmits different frequencies from the point where it receives the frequency to the corresponding point in the brain.
Tinnitus-How it works
How is tinnitus caused?
When a particular frequency range in the cochlea is damaged and no longer sends information to the brain, tinnitus may be caused. This may sound strange at first as tinnitus is caused by the brain NOT receiving signals rather than receiving too many.
In order to understand this, we need to explain one more piece the of hearing puzzle: what do you hear when there is nothing to hear? Your brain is actually hearing a steady state of sounds, however soft, at every frequency simultaneously. Your brain notifies you of hearing sounds only when it detects a pattern in the consistent noise it’s receiving.
So, when you stop receiving signals from a particular frequency, the brain can no longer detect any patterns so you will at first hear nothing at that frequency. If you don’t hear anything at a particular frequency at first, why do you eventually hear too much at that frequency?
Redistribution and use of “Brain-Space”
Your brain is exceptional and is extremely good at reusing space. For example, if you are blind your brain will often convert the areas traditionally used for image processing to process audio, smell, and taste sensations instead. In the case of tinnitus, your brain reuses the space for other frequencies. It immediately recognizes that you no longer have a use for the space reserved for the frequencies that are damaged in your cochlea.
The frequencies near the damaged frequencies are given extra processing power, therefore, they are more sensitive to detecting patterns. Furthermore, they also tend to spontaneously fire more frequently. Unfortunately, that means they detect sounds much more regularly than other frequencies are detected, prompting the brain to create ringing or tinnitus.
That extra firing of neurons that occurs spontaneously in the brain is interpreted by the rest of the brain as sound. Hence, the conscious brain sees activity in the hearing part of the brain and interprets it as ringing.