Seeing music as colors.
Learning Objectives - Synesthesia
What is Synesthesia ?
Synesthesia is the ability to perceive through your senses information you receive intellectually. This can be experienced as associations of multiple senses, when the stimulation of one sensory system leads to an experience in another system. Why do we separate each sense; taste, smell, sight, sound, and touch? Yes, it is possible to have a blending of our senses in our experience the world.
Synesthesia is a neurological condition in which two or more senses experienced separately are involuntarily joined together. For instance, some synesthetes experience color when they hear sounds or read words. Others experience tastes, smells or shapes.
Statistics vary between one in 23 people have Synesthesia  and ten people in a million have Synesthesia. Females outnumber males 6 to 1.... There is a strong link between Synesthesia and Photographic Memory. Many Synesthetes used their Synesthesia as a mnemonic aid. 
Synesthesia examples include; Seeing music as colors. Taste salt and see colors. Days of the week or months appear as colors. Numbers have shapes or colors. Feeling flavors as shapes. Cross-modal association is the comparison of one sense to another.
The word synesthesia comes from two Greek words, syn (together) and aisthesis (perception or sensation). Therefore, synesthesia literally means 'joined perception.' When one sensation leads to an experience of a second perception.
Cyto-architecture is a biology term used to describe the study of the arrangement of cells and how this affects the performance of each organ. Often referred to as study of the brain structure, 'cyto' means 'cells' and 'architecture' originates from Greek arkhitekton 'master builder.' Studying the architecture of the brain, is analogous to the study of buildings, their manner of construction and the arrangement of their parts. As recently as 2002 scientists discovered photoreceptors called ganglion cells (RGC) in our eye's retina that respond to light and send signals to our circadian system. Scientists continue to search for understanding of the brain circuits, receptors, and their functions. 
Synesthesia is part of the science of light and sight and this is why it is included here in ChromaTherapyLight.
"The colours my daughter 'sees' for each musical note."
Image by Jess, Photo by Andrew Bullock, 2009 
Chromesthesia is also termed sound-color synesthesia.
Criteria for Synesthesia 
Testing for Synesthesia
What is the Synesthesia Battery?
This battery of tests provides a standard battery of questions, tests and scoring. This test is available to the whole community of researchers and synesthetes for their use in making scientific progress. Your data will be kept entirely private, for use only by yourself, and by a researcher if you provide a valid email address for one.
Jason Padgett - Acquired Synesthesia and Savant Syndrome
Stuck by Genius: How a Brain Injury Made Me a Mathematical Marvel [book] by Jason Padgett and Maureen Ann Seaberg.
In this book, Jason Padgett discusses his recovery from head injury and recognizing his newly acquired math observations and insight about Pi, Fractals, and Fibonacci, termed Mathematical Synesthesia
Kandinsky and Other Artists
Vasily Kandinsky (1866-1944) is believed to have been a synesthetic artist who used sensory fusion in his art, composing paintings and music. His one-act opera of 1912 'The Yellow Sound' included color, light, dance, and sound. Thomas De Hartmann, Kandinsky's friend composed the music.
Many artists and composers have been quoted as saying they hear the colors or picture the color of the music.
Visit the American Synesthesia Association for articles, conferences, and support. Additional groups can be found is UK and Canada.
History and Research
In 1892, Wellesely College, Associate Professor of Psychology, Mary Whiton Calkins, published her 28 page paper: A Statistical Study of Pseudo-Chromesthesia and of Mental-Forms
In the 1970's Neurologist, Dr. Richard E. Cytowic, began studying and writing about Synesthesia, some of his books are listed below.
Books on Synesthesia