Koelsch et al. (see Current Biology vol. 19, 2009) carried out a study where parts of classical piano sonatas were played to people who considered themselves non-musical. The sonatas were played either by professional musicians or by computers. The sound from human or computer was almost indistinguishable however the subjects' brains showed considerably more electrical activity and their skin had a bigger conductance response (which varies with sweat production as a result of an emotional response) when listening to music played by a human.
The volunteers' brains showed clear electric activity in response to unexpected chords and changes in tonal key, which indicated that, despite not playing instruments or knowing music theory themselves, their brains were able to respond to the musical grammar in the sonatas. This response was enhanced, however, when the sonatas were played by musicians rather than a computer. If emotional reactions to musical changes were stronger when played with slight musical expression, the musical performance of other individuals could be viewed in the same way as interpreting language, or may even have some connection to the part of the brain which responds to language. It is interesting that a musical piece can naturally be perceived as emotional even by people who claim to have no musical training.