The sounds are described as ringing, buzzing, roaring, hissing or whistling
Scientists believe they are a step closer to curing tinnitus after they have found what could be the root cause of ringing in the ears.
Studies show hearing loss can go hand-in-hand with over-excitable nerves within brain areas that process sound.
This uncontrolled nerve activity causes the noises that plague people with tinnitus and appears to be down to gene changes, Neuroscience reports.
And it raises the hope of treatment by silencing nerve activity, experts say.
Although the studies carried out by the Australian researchers were in guinea pigs - the animal rather than the human variety - they believe their findings will ultimately help people with tinnitus.
Indeed, Belgian neurosurgeon Dirk De Ridder has tried implanting electrodes directly into the brain of sufferers to permanently normalise the overactive neurons.
He has had some successful results, although one of his patients repeatedly reported an out-of-body experience as a side effect.
In the latest study, researchers at the University of Western Australia studied what was happening inside the brain and found increased activity in nerves in the auditory brainstem where sounds are processed.
And this was linked to changes in the genes involved in regulating the activity of the nerve cells.
This meant pathways that normally keep a lid on nerve signal transmission were blocked and others were more excitable than usual.
Lead researcher Professor Don Robertson said: "Identifying genes associated with spontaneous nerve cell activity is crucial.
"It means that it may be possible to use drugs to block this activity and treat conditions such as tinnitus in the future."
Dr Ralph Holme of RNID, which funded the work, said: "Tinnitus affects seven million people in the UK, yet there are no safe or effective ways of alleviating this stressful condition.
"It has remained an enigma for scientists and clinicians alike and we are extremely excited about the significant progress this research has made into understanding its causes."
Vivienne Michael, chief executive of Deafness Research UK, said: "The new research gives us a better understanding of how and why tinnitus and hearing loss so often go hand in hand.
"Tinnitus is a blight on the lives of millions, and any new research that may offer hope for tinnitus sufferers is both exciting and warmly welcomed."
Over a third of the UK population will suffer from tinnitus at some point in their lives and about one in 100 will experience serious problems with long-term, established tinnitus.
Tinnitus is often associated with some degree of hearing loss.