Auditory
Hallucinations:
What's It Like Hearing Voices?
Hearing what others can’t hear
September 27, 2003
By Ralph Hoffman
Professor of Psychiatry at Yale University
You are in a crowd when you hear your name. You turn, looking for the
speaker. No one meets your gaze. It dawns on you that the voice you heard must
have sprung from your own mind.
This foray into the uncanny is as close as most people come to experiencing
auditory hallucinations or
“hearing voices,” a condition that affects 70% of
patients with
schizophrenia and 15% of patients with mood disorders such as mania or
depression. For these individuals, instead of hearing just one’s name,
voices produce a stream of speech, often vulgar or derogatory (“You are a
fat whore,” “Go to hell”) or a running commentary on one’s
most private thoughts.
The compelling aura of reality about these experiences often produces
distress and disrupts thought and behavior. The sound of the voice is sometimes
that of a family member or someone from one’s past, or is like that of no
known person but has distinct and immediately recognizable features (say, a
deep, growling voice). Often certain actual external sounds, such as fans or
running water, become transformed into perceived speech.
One patient described the recurrence of voices as akin to being “in a
constant state of mental rape.” In the worst cases, voices command the
listener to undertake destructive acts such as suicide or assault. But hearing
voices is not necessarily a sign of mental illness, so understanding the
mechanics of auditory hallucinations is crucial to
understanding
schizophrenia and related disorders.
For example, your occasional illusionary perception of your name spoken in a
crowd occurs because this utterance is uniquely important. Our brains are
primed to register such events; so on rare occasions the brain makes a mistake
and reconstructs unrelated sounds (such as people talking indistinctly) into a
false perception of the spoken name.
Hallucinated voices are also known to occur during states of religious or
creative inspiration. Joan of Arc described hearing the voices of saints
telling her to free her country from the English. Rainer Maria Rilke heard the
voice of a “terrible angel” amidst the sound of a crashing sea after
living alone in a castle for two months. This experience prompted his writing
the Duino Elegies.
How can we understand differences between an inspired voice, an isolated
instance of hearing one’s own name, and the voices of the mentally ill?
One answer is that “non-pathological” voices occur rarely or perhaps
only once. Not so for the person with mental illness. Without treatment, these
experiences recur relentlessly.
Brain imaging studies have found that parts of the temporal lobe activate
during these hallucinations. Our research at Yale University, as well as
studies conducted at the Institute of Psychiatry in London, also detected
activation in an area of the brain known as Broca’s region during
production of “inner speech” or verbal thought.
One theory is that voices arise because Broca’s area “dumps”
language outputs into parts of the brain that ordinarily receive speech inputs
from the outside. To test this theory we are using trans-cranial magnetic
stimulation (TMS) to reduce the excitability of portions of the temporal lobe
and Broca’s region.
So far, most patients appear to experience significant improvements from TMS
directed to both brain regions, with improvements lasting from two months to
over a year. These results, although preliminary, suggest an alternative
treatment if validated in larger-scale studies.
What remains unaddressed is the root cause of abnormal brain activations. We
are pursuing three intertwined ideas. The first is based on studies suggesting
that schizophrenia patients suffer from reduced brain connectivity. As a
result, certain groups of neurons, such as those responsible for producing and
perceiving language, may begin to function autonomously, beyond the control or
influence of other brain systems. It is as if the string section of the
orchestra suddenly decided to play its own music, disregarding everyone else.
The second idea is that deprivation of social interaction—namely human
conversation—makes the brain more likely to produce hallucinated
conversations. Often one of the first
signs of
schizophrenia—occurring well before manifestations such as hearing
voices—is social
isolation.
Indeed, sensory deprivation can produce hallucinations in the sense mode
that is deprived. An example is Charles Bonnet Syndrome, where visual
impairments in the elderly can produce visions of human figures. Could the
absence of actual spoken human conversation—a cornerstone of day-to-day
human intellect and creativity—produce hallucinated conversations? Recall
the extreme isolation that preceded the appearance of Rilke’s startling
voice.
Third, heightened emotions may play a role in producing voices. Indeed,
heightened emotionality prompts the brain to produce information consonant with
that emotional state. For example, a low mood favors generation of thoughts
that are themselves depressing. It is possible that intense states of emotion
could pre-select and perhaps elicit from the brain certain verbal messages
having the same emotional charge.
Verbal messages expressed by voices often are highly emotional. Moreover,
when schizophrenia begins, these persons are often in states of extreme fear or
elation. It could be that these powerful emotional states increase the
propensity of the brain to produce corresponding verbal “messages.”
This would account for the fact that voices also emerge during states of
extreme, but incidental, emotionality brought on by inspired thought, mania,
depression, or ingestion of certain drugs. Here the voices disappear when the
emotional states return to normal. The
brains of schizophrenia sufferers may be
vulnerable to becoming “stuck” in these hallucinatory states.
Our hypothesis is that voices arise from different
combinations of these three factors—reduced brain integration, social
isolation, and high levels of emotionality. This view has become the focus of
efforts to understand and help patients with mental illness quiet their minds.
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