The question of what a deaf person “hears” in their head relates to language, sensory experience, and the brain’s ability to adapt. An individual’s internal world is not solely defined by the presence or absence of sound, but by the sensory modality in which they first acquired language. The internal experience of a deaf person is highly diverse, varying significantly depending on whether their deafness is congenital or acquired, and whether their primary language is spoken or signed. This internal landscape reveals that thought is fundamentally non-auditory, and the brain, when deprived of one sense, often repurposes those neural pathways for others.
The Nature of Silence and Internal Body Sounds
The concept of “silence” for a profoundly deaf individual is often not an absolute sensory void. Even without external auditory input, the body is a source of continuous, non-acoustic internal sensations that can be perceived, including somatosensory and vibratory feedback that a hearing person might overlook.
Individuals with certain types of hearing loss, like conductive loss, may experience internal sounds more prominently, as bone conduction can amplify the sounds of chewing or breathing. However, for those with profound sensorineural deafness, the perception of internal body functions, such as a heartbeat or stomach rumbling, is often a physical sensation or vibration rather than a distinct sound. This constant, subtle stream of information contributes to the overall non-auditory sensory baseline.
The Form of Internal Monologue and Thought
Contrary to the assumption that all thought is auditory, the internal monologue of a deaf person demonstrates that language and cognition are highly flexible. The way an individual thinks internally is directly shaped by their primary language modality. This internal dialogue is a silent, conceptual process.
For individuals whose first language is a sign language, their internal thought often manifests as “inner signing.” This is a visual, spatial, and movement-based process, where they see signs being performed in their mind’s eye without physical movement. The thought process becomes a dynamic, visual stream of signs and conceptual imagery.
Deaf people raised using spoken language, or those who lost their hearing later in life, may think in ways that incorporate the motor memory of speech. This can involve visualizing the shape of words, imagining mouth movements, or experiencing the muscle sensations of articulation without producing sound. Regardless of the form—visual signs, mouth shapes, or written text—the complexity of their inner thought is equivalent to that of a hearing person.
Phantom Sounds: Tinnitus and Auditory Hallucinations
A striking phenomenon that can occur is the perception of “phantom sounds” that have no external source. Tinnitus, often described as ringing, buzzing, or hissing, is prevalent among individuals with acquired hearing loss and is considered a simple form of auditory hallucination. The brain, seeking to compensate for the lack of external input, generates its own neural signals, resulting in the perception of continuous sound.
More complex auditory hallucinations, manifesting as voices or music, also occur in deaf populations and are linked to the severity of hearing impairment. Studies suggest the prevalence of complex auditory hallucinations, where the perceived sounds have meaningful content, can be around 16 to 24 percent in individuals with hearing loss. This is hypothesized to be a consequence of auditory deprivation, causing the brain’s auditory cortex to become hyper-excitable as it attempts to fill the sensory gap.
The experience of these phantom sounds is far less common in those born profoundly deaf, as their auditory processing pathways never developed the same sound-based expectation. The phenomenon is therefore more closely associated with acquired sensory loss than with congenital deafness.
Brain Plasticity and Sensory Reorganization
The scientific explanation for the diverse internal experiences of deaf individuals lies in neuroplasticity, the brain’s ability to reorganize itself in response to sensory change. When the auditory cortex is deprived of sound input, it does not remain dormant; instead, it is often repurposed by other senses in a process known as cross-modal plasticity.
Research shows that areas of the brain normally dedicated to processing sound can be recruited to process vision or touch. For example, the auditory cortex in deaf individuals may become more active when they are viewing sign language, processing peripheral visual motion, or experiencing tactile vibrations. This sensory reorganization is believed to enhance the remaining senses, providing a biological foundation for the heightened visual and somatosensory awareness often observed in the deaf community.
This neural adaptation explains why internal thought processes are typically visual and spatial in nature, and it also provides insight into the mechanism of phantom sounds. The recruitment of the auditory cortex by other senses demonstrates the brain’s drive to utilize all available neural resources.