The perception of sound without any corresponding external source is known as tinnitus. This sound is frequently described as a ringing, buzzing, hissing, or clicking noise that only the individual can hear. Experiencing this internal sound most noticeably when the environment is quiet is a very common phenomenon. This increased awareness suggests the experience is linked to how the brain processes sound rather than just a problem in the ear itself.
Defining Tinnitus and Its Prevalence
Tinnitus is not a disease but a symptom arising from an underlying change within the auditory system. The vast majority of cases (over 99%) are classified as subjective tinnitus, meaning the sound is only audible to the person experiencing it and results from changes in neural activity within the brain’s auditory pathways.
In rare instances, tinnitus is objective, meaning a doctor can hear the sound during an examination, often using a stethoscope. This form is caused by physical sources like turbulent blood flow or muscle spasms near the ear structures. Tinnitus affects approximately 10 to 15% of the adult population globally. While mild and intermittent for most, the constant noise can become disruptive for a significant minority.
The Paradox of Silence: Why Perception Changes
The experience of tinnitus becoming louder in a quiet room relates directly to acoustic masking. During the day, environmental sounds—such as traffic, ventilation, or conversation—mask the internal tinnitus signal, making it less noticeable or inaudible.
When a person enters a silent environment, the ambient noise disappears. This lack of external stimulation activates central auditory gain, a neurological process where the brain attempts to compensate for reduced sensory input by turning up the volume on its internal signals.
This compensatory increase in neural activity makes the previously masked signal more prominent. The brain seeks input and amplifies the sound generated internally by the auditory system. This mechanism explains why the ringing is often most disruptive when trying to fall asleep or in a soundproof space.
Common Causes and Underlying Mechanisms
Inner Ear Damage and Noise Exposure
Damage to the delicate hair cells within the inner ear, known as the cochlea, is the most frequent underlying cause of subjective tinnitus. These sensory cells translate sound waves into electrical signals for the brain; when damaged, they may send aberrant signals. Prolonged exposure to loud noise, such as from machinery, concerts, or headphones, is a primary factor in this cellular damage.
Age-Related Hearing Loss and Medications
Age-related hearing loss (presbycusis) involves the gradual deterioration of these cochlear cells over time. As the brain receives less external sound information due to this decline, it activates the central gain mechanism to fill the void. Beyond the auditory system, certain medications are known to be ototoxic, meaning they can chemically damage the inner ear structures and induce tinnitus. Over 260 prescription and over-the-counter drugs have been reported to cause this side effect.
Physical and Joint Issues
Physical blockages, such as excessive earwax buildup, can temporarily induce or worsen tinnitus by changing pressure in the ear canal. Issues with the temporomandibular joint (TMJ) can also cause tinnitus because the muscles and nerves in that area are closely connected to the hearing apparatus. Treating these specific physical issues can sometimes lead to a full resolution of the sound.
When to Seek Professional Evaluation
While tinnitus is common, certain accompanying symptoms warrant prompt medical attention from an audiologist or an ear, nose, and throat (ENT) specialist.
A sudden onset of tinnitus, especially if it occurs in only one ear (unilateral presentation), requires immediate evaluation. This can signal underlying conditions like sudden sensorineural hearing loss.
Consultation is also advised if the perceived sound pulses or beats in sync with your heartbeat, a condition called pulsatile tinnitus. This rhythmic sound may indicate a vascular issue requiring diagnostic testing. Additionally, if tinnitus is accompanied by vertigo, severe dizziness, facial weakness, or significant ear pain, assessment is necessary to rule out more serious disorders.