Brent, L., Weaver, D. 1996. The physiological and behavioral effects of radio music on singly housed baboons. Journal of Medical Primatology 25(5), 370-374.

The response of four singly caged baboons to radio music was measured using behavioral and physiological indices. Heart rate and blood pressure, measured through a tether system, as well as behavior, were recorded during a two-week period in which radio music was available in half of the samples. Vocalization [of the single-housed subjects] was twice as high when the radio was off. Blood pressure did not vary with radio condition, but the heart rate was significantly lower when the radio was playing.