The effect of music on cognition has long fascinated both lay-people and neuroscientists alike, the latter of which have researched the way music affects our brains. When we hear music we like, be it Motzart or Miley Cyrus, our brain releases dopamine, a neurotransmitter associated with pleasure. But what is it that this dopamine is reacting to? In 1956, musicologist Leonard Meyer published a study stating that it was the interaction of music with our expectations --- either meeting, countermanding or suspending them --- that causes our brains' reactions.
Parsing out the exact effect that listening to music has on the mind is currently impossible due both to the complexity of the subjects involved and the enormous amount of variables. However, everyone is familiar with the effect that music can have on mood. Songs we like make us happy, sorrowful tunes can make us sad, rollicking beats can make us want to dance and strange new tonal combinations --- like Stravinsky's riot-starting "Rite of Spring" --- can upset us disproportionately. This psychological impact is irrefutable, even without a specific understanding of the mechanisms at work, but can music have more concrete effects?
Back in the 1990s, a group of researchers at the University of California in Irvine found that subjects performed better on cognition tests after listening to Mozart. Called the "Mozart Effect," this study was quickly picked up by the media, leading to widespread claims that listening to Mozart made you smarter. This made sense to the public, which had long associated intelligence with classical music, yet the results could not be and have not been repeated. Furthermore, the study compared performance between subjects who listened to Mozart versus subjects who sat in silence. Those that heard the music likely enjoyed it over silence, leading to "enjoyment arousal" --- an improvement of mood that led to an improvement in test scores.
Unfortunately, there is no song or style of music that will magically boost your brain power. Study after study has shown that music of any style, volume or tempo does not have a statistically significant effect on test scores, whether played during the test or while students were studying. However, students of music --- that is, those who study an instrument --- reliably perform better on standardized tests covering all subjects, including the SAT. Even when music education came at the cost of classroom instruction, these students matched or outperformed their peers. While the exact mechanism is not understood, it is clear that musical training teaches discipline, focus and memory, all of which are useful skills in academics.
More broadly, studying music or a musical instrument also improves general cognitive performance outside of test scores. Music students are the most likely to be accepted into medical school, with two-thirds of music majors applying for medical schools receiving acceptance letters --- the highest of any major. Children studying music can focus more easily, which aids learning and cognition; and skill at differentiating sounds, which music teaches, can help students learn to read. On the biological level, classically-trained male musicians were found to have 5 percent greater brain volume based on a study by Dr. Gottfried Schlaug of the Best Israel Deaconess Medical Center in Boston.