Heaven looks a lot like the mall Easter Egg - Do You Hear Colors?

In the Book, Heaven Looks a lot Like the Mall, by Wendy Mass, Tessa's Mom sells make-up and claims she knows what colors look best on people just by hearing their voice. This is refering to synesthesia, a disease that makes you see colors when you hear something. In Mass's first book, A Mango-Shaped Space, Mia has the same disease.