In A Mango-Shaped Space by Wendy Mass (2004), the main character shares her experiences as a Synesthete.  While this book is not a non-fiction book, it is an account based on truth, of a 13-year-old girl discovering new things about herself - specifically, her synesthetic ability. She has very similar letter, number, and word-color associations to Abbigale. The character also sees shapes of objects when she hears sounds.  These shapes have specific colors too.  So when the character hears her cat meow, she sees a shape of her cat in a mango color.  I decided to see if Abbigale does this as well.  Sure enough, this special ability happens to Abbigale as well.  See the sounds and shapes chart for specifics:

When asked how she sees these colored shapes, she was a little confused as to how to describe it.  She had immediate answers for the shapes/colors that she saw.  She said it just goes over the boxes.  I asked if this was distracting or scary to her and she said it made it hard to do things sometimes if the noises were loud.  Loud rock music made bold dark colors that got mixed up sometimes.  Other loud noises did that sometimes too.  She didn't think it was scary.  She did say that sometimes she buries her head.  When she told me this, I recalled many times when she was a baby or toddler and how she always wanted me to carry her in a sling especially if there were loud noises or crowded areas such as the zoo.  Sometimes (when she was toddler) she would bury her head in the sling and not look.  I also recalled that at these moments she did not want to speak or address others.  In most of the research that I reviewed, synesthesia is very deliberately labeled a gift rather than a disability.  Most synesthetics do not want their "specialness" to go away.  However, one study (Baron-Cohen, 1996) uses the term "suffers": "...in this form of Synaesthesia it leads to massive interference, stress, dizziness, a feeling of information overload, and a need to avoid those situations that are either too noisy or too colourful....[in this case] of Synaesthesia leading to social withdrawal, and interference with ordinary life."  It seemed like this happened to Abbigale occasionally.

Through the use of MRI and other technology, Synesthesia has been linked to the limbic system, the part of the brain that helps to monitor emotions, reactions, and elicit emotional response  (Ward, 2002).  Abbigale has always been labeled "shy" by anyone that meets her.  New situations, people that she doesn't feel very comfortable around (even ones she knows such as a teacher or grandmother), times alone in the house, and crowded events elicit a shy withdrawal response from Abbigale.  In some cases, she physically can't speak.  This response goes away fairly quickly once she becomes familiar with the situation or people or if it quiets down.  However, in some cases she needs to have "quiet time," usually in my lap, for 20-30 minutes to recover.  Most folks just say to her, "Oh, she is shy," and they smile at her.