Tinnitus doesn’t have a single root cause. It’s the end result of a chain reaction that usually starts with damage to the inner ear and continues with changes in how the brain processes sound. About 14.4% of adults worldwide have experienced it, and roughly 2% deal with a severe form. Understanding what drives it means looking at both the ear and the brain, because tinnitus lives at the intersection of the two.
How Inner Ear Damage Creates a Phantom Signal
The most common starting point is damage to the tiny hair cells inside the cochlea, the spiral-shaped structure in your inner ear. These cells convert sound vibrations into electrical signals that travel to the brain. When they’re healthy, they have a baseline level of electrical activity even in silence. But when they’re damaged, whether from loud noise, aging, or toxic medications, that baseline activity goes haywire.
Here’s what happens at the cellular level. Inner hair cells sit partly “open” at rest, allowing a small electrical current to flow through them. When outer hair cells are destroyed or their tiny hair-like projections (stereocilia) are bent or broken, the electrical environment inside the cochlea shifts. This shift pushes the inner hair cells into a state of prolonged activation. They start releasing their chemical messenger continuously, firing signals down the auditory nerve as if a sound were present. Acute noise exposure, for instance, has been shown to physically alter the roots of stereocilia, which may explain why tinnitus often appears immediately after loud sound exposure.
This type of tinnitus, generated at or before the auditory nerve, produces neural activity that closely resembles what a real sound would create. That signal propagates all the way up to the auditory cortex. Whether you actually perceive it as a sound depends on how strong the signal is and whether higher brain regions are paying attention to it.
The Brain’s Role: Failed Noise Cancellation
If damaged hair cells were the whole story, tinnitus would simply stop when the damage healed or stabilized. But for many people, it persists long after the initial injury. That’s because the brain reorganizes itself in response to the lost input, a process called maladaptive plasticity.
When the brain stops receiving normal signals from a damaged part of the cochlea, neurons in the auditory system don’t just go quiet. They become hyperactive, turning up their sensitivity as if straining to hear what’s no longer there. This happens across multiple levels of the auditory pathway, from the brainstem to the auditory cortex. Animal studies have confirmed that tinnitus is associated with dysfunctional synaptic plasticity in both auditory and emotional brain regions.
A critical piece of the puzzle involves a region in the front of the brain called the ventromedial prefrontal cortex (vmPFC). In people without tinnitus, this area acts as a volume knob for unwanted neural noise. It sends inhibitory signals through a relay station near the auditory processing center, effectively canceling out meaningless activity before it reaches conscious awareness. Researchers have described chronic tinnitus as a failure of this noise-cancellation circuit. When the vmPFC is compromised, whether through structural differences, stress, or other factors, it becomes less efficient at suppressing the aberrant signals, and tinnitus persists.
Importantly, the system that determines whether you hear the tinnitus is separate from the system that determines how much it bothers you. Tinnitus distress is linked to a different brain region, the anterior insula, which processes emotional salience. This is why two people with identical hearing damage can have vastly different experiences: one barely notices the ringing, while the other finds it debilitating.
Hearing Loss Is the Most Common Trigger
In most cases, tinnitus arises from acquired and sustained hearing loss. That hearing loss can come from many sources, but the mechanism is broadly the same: fewer functioning hair cells, altered electrical signaling in the cochlea, and compensatory changes in the brain.
Noise exposure is the leading preventable cause. A single blast of extremely loud sound or years of moderate overexposure can both destroy hair cells permanently. Age-related hearing loss is another major driver, which is why tinnitus becomes more common in older adults. Conditions like vestibular schwannoma (a benign growth on the nerve connecting the ear to the brain) cause tinnitus in about 9 out of 10 affected people, typically in just one ear.
Medications That Damage the Ear
Certain medications are directly toxic to the inner ear and can trigger tinnitus as a side effect. The major categories include high-dose aspirin, macrolide antibiotics like azithromycin (especially at high doses over long periods), platinum-based chemotherapy drugs like cisplatin, and loop diuretics used for heart failure and kidney disease. Some newer biologic drugs used in immunotherapy and gene therapy have also been linked to hearing damage. In many of these cases, tinnitus may resolve once the medication is stopped, but not always.
When the Jaw and Neck Are Involved
Not all tinnitus originates in the ear. A distinct subtype called somatosensory tinnitus is driven by problems in the jaw, neck, or head. Clenching your jaw, grinding your teeth, or having a misaligned temporomandibular joint (TMJ) can all feed abnormal signals into the auditory system.
The connection runs through the dorsal cochlear nucleus, an early processing station in the brainstem where auditory and body-position signals converge. Muscle contractions in the head and neck send information through the somatosensory system to a relay point that projects directly onto this auditory hub. When those signals are excessive or abnormal, they can increase neural firing in the cochlear nucleus and produce or modulate tinnitus. This is why some people can change the pitch or volume of their tinnitus by moving their jaw or turning their head. Branches of the trigeminal nerve, which serves the face and jaw, have been shown to directly influence neurons in this region.
Pulsatile Tinnitus: A Vascular Cause
Pulsatile tinnitus is a rhythmic whooshing or thumping that matches your heartbeat. Unlike the more common ringing type, this is often an objective sound, meaning a clinician can sometimes hear it too. It’s generated by blood flow near the ear, and it almost always has an identifiable physical cause.
The list of potential sources includes abnormal connections between arteries and veins (arteriovenous malformations or fistulas), narrowing of the carotid artery from plaque buildup, abnormalities of the jugular bulb or sigmoid sinus (venous structures near the ear), small tumors called glomus tumors, and increased pressure inside the skull from a condition called idiopathic intracranial hypertension. A thin or missing bone between the sigmoid sinus and the middle ear can also transmit the sound of blood flow directly to the hearing apparatus. Because these causes are structural, pulsatile tinnitus is often treatable once the source is identified through imaging.
Thyroid Problems and Metabolic Links
Endocrine disorders can quietly set the stage for tinnitus. People with low thyroid function face an increased risk, and roughly 40% of adults with hypothyroidism have inner ear hearing loss in both ears. A large study using Taiwan’s national health database found that individuals who had hearing loss, vertigo, or insomnia alongside hypothyroidism were especially likely to develop tinnitus. Overactive thyroid function has also been implicated.
The encouraging finding is that treating the thyroid disorder frequently improves or even eliminates the tinnitus. Restoring normal thyroid levels can reverse the metabolic conditions that were stressing the inner ear. However, in some cases, thyroid medications themselves can trigger tinnitus, particularly at high doses, which makes careful dose management important.
Why It Becomes Chronic
The shift from temporary to chronic tinnitus appears to depend on how the brain responds to the initial signal. A protein called brain-derived neurotrophic factor (BDNF), which supports neuron survival and healthy signaling throughout the auditory pathway, plays a key role. When BDNF levels drop, neurons in the auditory system become more vulnerable to damage and more prone to the kind of runaway plasticity that locks tinnitus in place. Reduced BDNF has been linked to both increased susceptibility to hearing damage and the subsequent persistence of tinnitus.
Stress and emotional state can amplify this process by affecting the limbic system, the brain’s emotional circuitry. But the research is clear that a negative emotional reaction isn’t required for tinnitus to become chronic. The noise-cancellation failure in the prefrontal cortex can happen independently of mood. Stress makes things worse, but it isn’t the gatekeeper.