From a study by Riia Milovanova, Mari Tervaniemic, Fiia Takiob, and Heikki Hämäläinenb: (pdf file)
To increase our understanding of the phonemic processing skills of musical and nonmusical subjects, the Dichotic Listening task was performed in children and adults with varying degrees of musical aptitude. The roles of maturation and musical training were also investigated. The results showed superior left ear monitoring skills among the adults who practised music regularly [emphasis added]. This may indicate altered hemispheric functioning. Other musically talented subjects did not have the ability to control left ear functioning in an equal manner, for instance, the performance of musical children and their non-musical controls in the forced–left / left ear condition did not differ. Thus, regular music practice may have a modulatory effect on the brain’s linguistic organization and therefore, the beneficial effects of music on other cognitive skills should not be underestimated. [emphasis added]
These Finnish researchers have done a different kind of study; rather than focusing on grades or tests of linguistic ability, they have proved even that musicians hear differently with their left ears, and have guessed that the reorganization of the right side of the brain may account for the differences.
The Lady and the Unicorn: Hearing
Although it’s currently believed that it’s the left hemisphere that is responsible for phonemic and other kinds of linguistic processing, it’s entirely possible that the right hemisphere may have significant, yet-to-be-determined role to play in how we understand language. In any case, we have not yet understood the ways in which learning to play music changes the brain, and the effect may be yet more widespread and significant than we imagine at present.