Seeing Sound: The Fascinating World of Musical Synesthesia

For some people, music isn’t just sound, it is color. This phenomenon, known as chromesthesia, is a striking form of musical synesthesia in which sounds automatically evoke vivid visual experiences. Synesthesia, in general, is a neurological condition where stimulation of one sense triggers another. Musical synesthesia can take many forms—for instance, auditory-tactile synesthesia, where music produces sensations on the skin, or spatial-sequence synesthesia, where music seems to occupy specific locations in space. Among these, chromesthesia is the most visually striking and the most widely studied.

Humans have long been fascinated by connections between music and color. Thinkers like Pythagoras and Isaac Newton explored links between musical notes and colors, while Louis Bertrand Castel created the color organ to make music visible. In 1881, Georg Tobias Ludwig Sachs recorded the first personal account of these experiences, and Bleuler and Lehmann began systematic study of sound-to-color associations (View of Music-Color Synesthesia: A Historical and Scientific Overview, 2024). Even well-known composers, such as Alexander Scriabin, are thought to have had the condition.

What causes synesthesia? Genetics likely play a role, with genes like reelin guiding neuronal development. Neuroscientists debate exactly how it works in the brain: one theory points to extra connections between sensory areas, while another suggests that the brain’s usual “filters” between senses may be looser in synesthetes. One review (Bragança et al., 2015) proposed that even people without synesthesia have a kind of “latent synesthesia,” subtle cross-sensory links that help the brain connect sounds with memories, images, and emotions. These links may explain why music often sparks mental imagery and emotional associations, even in those without chromesthesia.

Modern neuroscience sheds further light on chromesthesia. Using Diffusion Tensor Imaging, researchers have found that people with music-color synesthesia show stronger connections between auditory and visual regions of the brain, especially the right inferior fronto-occipital fasciculus (IFOF), a tract linking auditory and visual areas (Zamm et al., 2013). This extra connectivity helps explain why sounds can automatically trigger colors for synesthetes.

But it’s not just brain structure, how music is performed also matters. One study found that synesthetes experienced more intense color responses when listening to human performances than to computer-generated versions, no matter how familiar they were with the instrument. While both synesthetes and non-synesthetes connected emotion and movement in music, synesthetes’ color experiences were shaped more by the sense of motion than by emotion alone. This shows that chromesthesia isn’t just a passive reaction: movement and expression in music can actively enhance the vividness of color experiences (Curwen et al., 2024).

Chromesthesia also seems to enhance mental imagery. Musicians with synesthesia report more vivid visual and auditory imagery than non-synesthetic musicians, even when imagining music without hearing it. Their involuntary cross-sensory activations appear to extend to conscious mental representations, suggesting that their brains simulate sensory experiences in richer, more vivid ways. This may help explain why synesthetic musicians often show heightened creativity and expressive abilities (Glasser, 2023).

Chromesthesia reminds us that perception is more than what we hear or see—it’s a deeply personal, multisensory experience. Studying synesthesia helps us understand how the brain connects senses, shapes imagination, and even influences creativity. These intertwined experiences show just how unique and extraordinary the human mind can be.

References 

Bragança, G. F. F., Fonseca, J. G. M., & Caramelli, P. (2015). Synesthesia and music perception. Dementia & Neuropsychologia, 9(1), 16–23. https://doi.org/10.1590/s1980-57642015dn91000004  Curwen, C., Timmers, R., & Schiavio, A. (2024). Action, emotion, and music-colour synaesthesia: An examination of sensorimotor and emotional responses in synaesthetes and non-synaesthetes. White Rose Research Online. https://eprints.whiterose.ac.uk/id/eprint/201649/1/s00426-023-01856-2.pdf 

Glasser, S. (2023). The Relationship Between Music-Related Types of Synesthesia and Mental Imagery in Synesthete Musicians. Music & Science, 6, 205920432311738-205920432311738. https://doi.org/10.1177/20592043231173810 

View of Music-Color Synesthesia: A Historical and Scientific Overview. (2024). UMN.edu. https://pubs.lib.umn.edu/index.php/aisthesis/article/view/4635/3133 

Zamm, A., Schlaug, G., Eagleman, D. M., & Loui, P. (2013). Pathways to seeing music: Enhanced structural connectivity in colored-music synesthesia. NeuroImage, 74, 359–366. https://doi.org/10.1016/j.neuroimage.2013.02.024