The experience of hearing internal body sounds, such as the subtle noise of your own blink, can be unsettling. Although unusual, this phenomenon is a recognized medical condition studied within otology, the branch of medicine focused on the ear. This heightened awareness of internal sounds points toward a specific anatomical variation in the inner ear. Understanding the underlying cause can provide significant reassurance regarding this unusual auditory perception.
The Mechanism Behind Hearing Internal Sounds
The underlying cause for hearing internal sounds like blinking is most often Superior Semicircular Canal Dehiscence (SSCD). This syndrome involves an anatomical defect where the dense temporal bone covering the superior semicircular canal is thinned or absent, a condition called a dehiscence. This canal is one of three fluid-filled loops in the inner ear that regulate balance.
The inner ear normally uses the oval and round windows to manage fluid pressure and dissipate sound energy. The dehiscence introduces a “third window” into this system, disrupting the normal mechanics of fluid movement and pressure transmission. This extra opening allows pressure waves from within the skull to transmit directly to the inner ear fluid.
When blinking or moving the eyes, muscles generate subtle pressure changes and vibrations. These vibrations travel through the dehiscence, stimulating the sensitive inner ear structures and leading to the perception of sound. This “third window” effect lowers the impedance for bone-conducted sounds, making normal internal functions audible.
Associated Symptoms and Daily Impact
Hearing a blink is part of a wider set of symptoms associated with SSCD that can impact daily life. One common experience is autophony, the abnormally loud hearing of one’s own voice, breathing, or other body noises. Individuals may hear their voice resonate loudly or perceive their own breath as a distracting roar.
The heightened sensitivity to bone-conducted sound results in several auditory symptoms:
- Pulsatile tinnitus, a rhythmic thumping or whooshing sound synchronized with the heartbeat.
- Amplified footfalls from walking or running.
- Low-frequency conductive hearing loss, where external sounds are muffled while internal sounds are amplified.
The syndrome also affects the vestibular system, which controls balance. Loud noises can trigger dizziness or a sense of motion, known as the Tullio phenomenon. Activities that increase pressure, such as coughing, sneezing, straining, or lifting heavy objects, can provoke vertigo or unsteadiness. This combination of auditory and balance issues often leads to a constant feeling of ear pressure or fullness.
Seeking Confirmation and Treatment Options
A comprehensive evaluation is necessary to confirm Superior Semicircular Canal Dehiscence and rule out other conditions. Diagnosis begins with specialized hearing tests, including an audiogram, which often reveals increased sensitivity to bone-conducted sound. Vestibular-Evoked Myogenic Potentials (VEMPs) testing is also used, as SSCD causes an abnormally large response in these inner ear reflexes.
The definitive confirmation relies on high-resolution Computed Tomography (CT) scans of the temporal bone. These imaging studies allow specialists to visualize the precise location and extent of the dehiscence. Diagnosis and treatment are typically handled by Otolaryngologists, often those with fellowship training in Neurotology, who specialize in disorders of the ear.
Management of SSCD varies depending on symptom severity. For those with mild or intermittent symptoms, a conservative approach is recommended, focusing on avoiding known triggers like loud noises or maneuvers that change pressure. When symptoms are severe and significantly affect quality of life, surgical intervention may be considered. The primary surgical goal is to plug or resurface the dehiscence, effectively closing the “third window.” Techniques include plugging the canal via a transmastoid approach or resurfacing the bone defect through a middle fossa craniotomy, with both procedures designed to restore the normal pressure dynamics of the inner ear.