People Who Hear in Colors

Artistic interpretation of chromesthesia
Artistic interpretation of chromesthesia. peacemakergirl-d567cpc

What do Duke Ellington, Tori Amos, John Mayer, Stevie Wonder, Mozart, and Jimi Hendrix have in common? For them, sound is not just an auditory phenomenon. All of these musicians had/have a rare condition called synesthesia, in which the usual boundaries between the senses appear to break down, sight mingling with sound, or taste with touch. For them, sound has color. This particular type of synesthesia is called chromesthesia.

People with chromesthesia hear sounds and these automatically and unintentionally make them experience colors. Some of those with chromesthesia find the colors are projected into space in front of them; others see it in their ‘mind’s eye’. Some only get the chromesthesia for spoken words, which are influenced by the voice’s accent, pitch, and intonation; others just for music. And while the majority of synesthetes, who are about six times as likely to be female as male, find their unusual sensory abilities enjoyable, in some cases synesthesia can be disruptive.

Even basic facts about synesthesia are still uncertain. Recent estimates from Cambridge University in England used a newspaper and magazine survey to estimate 1 out of 2,000 people reported synesthetic experiences.

Some scientists believe that synesthesia represents an innate difference in neurophysiology, others that it is a result of associations learned at an early age.

Some studies have found the smaller a person's visual cortex was — the part of the brain linked with vision —the more likely he or she experienced sound visually. One of the authors noted, “it would make perfect sense for smaller visual brains to make more use of the additional information provided by the ears.

In the real world, sources of light and sound are often identical, and combining them will be advantageous. Imagine you take a twilight walk in a forest and scare up some animal in the undergrowth. The best strategy for finding out whether you are dealing with a hedgehog or a bear will involve combining visual information, like moving twigs and branches, with auditory information, like cracking wood." Dr. de Haas explained.

PET scanning study, published in 1996 in the journal Brain by Dr. Eraldo Paulesu, Dr. Baron-Cohen and colleagues, compared brain functioning in six synesthetes to that in six members of a control group. The subjects, all women, were blindfolded and listened to sound cues delivered through headphones. Synesthetes, the researchers found, showed increased activation in some areas of the visual cortex when responding to sounds; control subjects did not.

The areas showing increased activity are not the same as those activated when someone is imagining images, said Dr. Baron-Cohen.

Most recently, the team of German researchers compared recordings of electrophysiological activity in the brains of 17 synesthetic subjects, who experienced color images upon reading letters or numbers, with recordings from 17 control subjects.

The results, said Dr. Thomas Muente, a neurology professor at Hanover who took part in the study, suggest that during synesthetic experiences, regions of the frontal cortex of the brain that control attention and also play a role in processing sensory information are inhibited.

Synesthesia also appears to run in families, leading some researchers to believe it has a genetic basis

Researchers collected DNA from 196 people from 43 families in which there were multiple members with synesthesia. They looked exclusively at auditory-visual synesthesia, the kind where sound triggers color, which is easier to diagnose than other possible forms.

They expected to find a single gene responsible for synesthesia, but they found that the condition was linked to regions on chromosomes 2, 5, 6, and 12 -- four distinct areas instead of one.

Brain scans have shown that people with synesthesia seem to have "cross-wiring" between brain regions, said Dr. V.S. Ramachandran, director of the Center for Brain and Cognition at the University of California, San Diego.

"Cross-wiring" was shown in a study led by J.A. Nunn at Goldsmiths College, London, which found that the visual areas of the brain were activated in response to sound in people for whom sound triggers color.

Given that a normal infant's brain has excess connections between brain regions, one hypothesis is that synesthesia results when the genes that "prune" these connections away are mutated, Ramachandran said. In other words, people with synesthesia may have brain connections that would normally disappear at an early age.

Children with synesthesia will often show signs of it in school because it slows down reading for some kids and makes lectures difficult to absorb for others. As awareness of learning differences grows in schools, more children are coming forward and explaining that they have trouble, leading to more diagnoses. Interventions may include written notes or books on tape for those whose synesthesia interferes with, respectively, listening or reading.


Goode, Erica (1999). When People See a Sound and Hear a Color. The New York Times. Accessed April 22, 2015 from

Dean, Jeremy (2014). 6 Intriguing Types of Synesthesia: Tasting Words, Seeing Sounds, Hearing Colours And More. Psychblog. Accessed April 22, 2015 from

Landau, Elizabeth (2009) Seeing color in sounds has genetic link. CNN. Accessed April 22, 2015 from

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