The claim that the left hemisphere is the seat of language, however, is a little different. That idea comes from observations that damage to the left hemisphere (for example, due to a stroke) is often associated with difficulties producing language, a problem known as aphasia. Similar damage to the right hemisphere is much less likely to cause aphasia. In fact, for most people, the left hemisphere does play a much more important role in the ability to speak than the right hemisphere does.

The Truth About The Left Brain / Right Brain Relationship : 13.7: Cosmos And Culture : NPR Wednesday, December 4, 2013 @ 9:44pm