Our brains have a map of our body, so that if we feel something in an individual part of our body, it activates the corresponding part of the brain's map. Sometimes these parts of the brain can be activated without the need for a signal from the corresponding body part.

Our hearing is no exception, and the parts of brain that deal with sound can sometimes be activated without the need for an external sound or any other vibration that our ears may pick up (such as our heartbeat or breathing).

Our brains are always active – it's how they work – but normally we filter out this background brain activity, unless something draws our attention to it.

For example, if you are reading this sitting down, you will probably not have been aware of the feeling of your back against the chair… until reading this drew your attention to it!

This is why people who experience tinnitus often notice that talking about it will make it more noticeable – their attention has been drawn to it.