Tinnitus has many possible causes, and in many individuals it is associated with changes somewhere in the auditory system rather than one identifiable lesion. Hearing loss from ageing or prolonged noise exposure is among the most common associations. Other causes include earwax blockage, middle-ear disease, inner-ear disorders, head or neck injury, certain medicines and disorders affecting the auditory nerve or central nervous system. Tinnitus can also occur without an obvious underlying abnormality on routine examination. The perceived sound is thought to arise from altered neural processing of auditory information, but the exact mechanism differs among people. Consequently, identifying an associated condition can sometimes improve tinnitus, but treating the associated condition does not always eliminate the perception.
Noise exposure is an important trigger for tinnitus. Very loud sounds can cause temporary changes in cochlear function or permanent injury to sensory hair cells and associated neural structures. Repeated exposure to loud music, industrial machinery, engines or other high-intensity sound can accumulate damage over time. Tinnitus may appear immediately after a loud event or develop alongside gradual noise-induced hearing loss.
Even when conventional hearing thresholds appear normal, subtle changes in auditory processing may exist, although the clinical significance of these findings varies. Protecting the ears from excessive noise is therefore relevant to prevention, but once persistent tinnitus has developed, simply avoiding all sound is generally not a treatment because excessive sound avoidance can increase sensitivity and awareness in some people.
Age-related hearing loss is another major association. As cochlear structures and auditory neurons undergo cumulative changes with age, reduced peripheral auditory input can be accompanied by compensatory changes in central auditory processing. One proposed mechanism involves increased central neural gain, in which auditory pathways amplify or reorganise their response when normal input is reduced. Changes in neural synchronisation and interactions between auditory and non-auditory networks may also contribute.
These mechanisms are active areas of research rather than a single proven explanation for every case. The important clinical point is that tinnitus can reflect altered auditory processing associated with hearing loss even when the person experiences the tinnitus as an apparently external or ear-localised sound.
Ear conditions can trigger tinnitus by altering sound transmission or sensory input. Impacted earwax can block external sound and change the acoustic environment of the ear canal. Middle-ear fluid, infection or eardrum abnormalities can alter mechanical conduction. Inner-ear disorders such as Ménière's disease can produce tinnitus together with hearing fluctuation, ear fullness and episodic vertigo. Damage to cochlear hair cells from ototoxic drugs or other insults can produce tinnitus alongside sensorineural hearing loss. Treating a reversible ear disorder can sometimes reduce or eliminate tinnitus, but persistent tinnitus may remain if the underlying auditory structures have been permanently affected.
Medicines can sometimes cause or worsen tinnitus, with the likelihood depending on the specific drug, dose and individual circumstances. High-dose salicylates are a well-known example, while some antibiotics, chemotherapy medicines and other drugs can have ototoxic effects. Medication-related tinnitus should be evaluated carefully because many medicines that have potential auditory adverse effects are prescribed for important medical reasons. The appropriate response is not automatically to stop the medicine; a clinician may consider dose adjustment, substitution or monitoring where appropriate. Recreational substances and excessive alcohol or caffeine intake are sometimes reported as tinnitus triggers by individuals, but the evidence is variable and effects can differ substantially between people.
Head injury and disorders affecting the auditory nerve can also produce tinnitus. A vestibular schwannoma may cause unilateral tinnitus together with asymmetric or progressive sensorineural hearing loss. Head or neck trauma can alter cochlear, neural or somatosensory pathways and may lead to new tinnitus. Temporomandibular joint disorders and muscular tension can sometimes influence tinnitus through connections between somatosensory input and auditory brain networks. Tinnitus that changes when the jaw, neck or head is moved may therefore have a somatosensory component. These presentations illustrate that tinnitus is not always generated exclusively by the cochlea and can involve interactions among several sensory systems.
Pulsatile tinnitus has a different range of possible causes because the perceived sound may reflect vascular or pressure-related phenomena. Turbulent blood flow, vascular narrowing or abnormalities, increased intracranial pressure and certain vascular malformations can produce rhythmic sounds that correspond to the heartbeat. Many causes are benign, but persistent unilateral pulsatile tinnitus should be assessed because some vascular conditions require investigation. The distinction between pulsatile and non-pulsatile tinnitus is therefore clinically important. A detailed history should establish whether the sound is synchronous with the pulse, whether it is one-sided and whether it changes with posture, exertion or pressure.
In many people no single cause can be established, and tinnitus may arise from a combination of hearing-related, neural, psychological and environmental factors. Stress and poor sleep do not necessarily create the initial auditory signal, but they can increase attention to tinnitus and amplify its perceived intrusiveness. Anxiety can also make the sound more salient, creating a reinforcing cycle of monitoring and distress. Conversely, improved sleep, reduced threat perception and habituation can reduce its impact. New unilateral tinnitus, pulsatile tinnitus, tinnitus associated with sudden hearing loss, severe vertigo or neurological symptoms warrants clinical assessment because these features can indicate an identifiable condition requiring specific investigation or treatment.
