Last Wednesday, Professor Koenig discussed a little bit about how blindness in children usually has little to no effect on their speech production. This makes sense due to the fact that their hearing is still intact and because hearing is a main component when dealing with speech. However, I'm sure most of have heard that blindness in a person usually causes a heightening of the other four senses, especially hearing.
A study done by graduate students under the direction of experimental psychologist, Dr. Robert Zatorre at the Montreal Neurological Institute of Canada's McGill University confirmed this popular thought. They found that the blind subjects were more likely to hear a difference in pitch perception and more accurately point out where a sound was coming from. They also found that the longer a person has been blind, the more accurate they were with their tests.
This plasticity in the brain is necessary to meet the survival needs of the person. However, it makes me wonder: Can this brain plasticity in the blind cause them to detect the non-native speech changes just as infants have the ability to do? Just as Professor Koenig said, Werker's Procedure tested to what age is a child unable to detect the sound change between Hindi and Salish language when raised in an English speaking home. They found that children between the ages of six to eight months were able to detect the sound changes but were unable to after the age of one (the results are shown below). I would like to test this same idea amongst the blind based on the idea that they have heightened hearing and might be able to detect the sound changes as well as the infants in Werker's study. I would like to compose a study just as Werker did; however rather than having the toys signal the sound change I would simple provide the person with a button they would push if they hear the sound change. It would be a very interesting study and I feel it would give us a better idea on the extent of plasticity and speech development in the brain.
Blindness Study: http://health.msn.com/health-topics/blind-people-hear-better-truth-or-myth-1