Research on music and the brain:

Gottfried Schlaug's Music and Neuroimaging Lab at Beth Israel Deaconess-
LINK: http://www.musicianbrain.com/#publications

NPR segment on how music affects the developing brain-
LINK: How Playing Music Affects the Brain

Great TED-ed talk on music and your brain!
"When you listen to music, multiple areas of your brain become engaged and active. But when you actually play an instrument, that activity becomes more like a full-body brain workout. What’s going on? Anita Collins explains the fireworks that go off in musicians’ brains when they play, and examines some of the long-term positive effects of this mental workout."
LINK: How playing an instrument benefits your brain - Anita Collins
Other peer-reviewed publications:
 
  1. Application of Therapeutic Harp Sounds for Quality of Life Among Hospitalized Patients (2014)

    Schneider, Diane M. et al.
    Journal of Pain and Symptom Management , Volume 49 , Issue 5 , 836 - 845
    http://www.sciencedirect.com/science/article/pii/S0885392414005582