Stevie Wonder never considered his blindness a "disadvantage," and he's proved his point for more than 50 years. But for all his fantastic talent, his blindness may have contributed to his skills nonetheless. Research has found overwhelming evidence to suggest that blind musicians' brains can be a lot more musically attuned than those of sighted musicians.
Changed brains. When blind individuals lose their sight at early ages, it's certainly a disadvantage. But it has interesting positive effects as far as musical sensitivity goes. Blind children's brains undergo radical changes in order to make better use of the sensory inputs they can gather. Numerous fMRI and lesion studies suggest that individuals blind since childhood repurpose large portions of their visual cortex in order to respond better to auditory stimuli. The younger children are when they lose their sight, the more powerful their auditory cortex can be, thanks to increased neural plasticity in place during infancy/early childhood/young childhood.
Ray Charles, for instance, went blind by age 7. Studies out of the University of Melbourne have found that people who go blind at younger ages develop better pitch discrimination and pitch-timbre discrimination than sighted people, regardless of their levels of musical training. Obviously musical training bolsters those abilities, but blind people seem to start with a more sensitive neural foundation. Blind subjects are also far better at determining the position of sounds using a single ear; everyone, sighted or blind, can determine position fairly accurately with two ears, but only blind people can do so using one.
Blind musicians are among the most celebrated in history. Blues pioneer Blind Willie Johnson. Opera star Andrea Bocelli. Even Homer supposedly first sang the Iliad and the Odyssey blind. Elton John, writing on Wonder for Rolling Stone's 100 Greatest Artists of All Time list (Wonder ranked No. 15), said, "Along with Ray Charles, he's the greatest R&B singer who ever lived ... He could play with Charlie Parker or John Coltrane and hold his own."
Though it has nothing to do with taste or creativity, blind musicians have proven again and again how often they have some abnormal technical ability. For instance, they are much more likely to enjoy absolute (i.e., "perfect") pitch than sighted musicians. In 2004, researchers from Beth Israel Deaconess Medical Center reported that absolute pitch occurs in approximately 60% of blind musicians, versus only 10% in sighted musicians. Wonder himself was born with absolute pitch.
Not the whole story: Despite this wealth of research, it's still not entirely clear how these highly developed auditory abilities translate into musical excellence — not even perfect pitch, as much as our culture has obsessed over the value of this gift. Yet all these adaptations do point to an overall more powerful and dynamic auditory cortex, which can respond to and manipulate sounds to a much more impressive degree than sighted musicians.
Make no mistake, though — in no way does blindness guarantee musical excellence. As Charles once famously said, "I don't think I'm good because I'm blind, I think I'm good because I'm good." He was right: No matter what, it takes a lot more than a good ear to become a musical genius.