Shenfield T, Trainor LJ, Nakata T. Maternal singing modulates infant arousal. Psychology of Music. 2003; 31(4): 365–375.
This study analyzed saliva samples of infants to reveal that infants with lower baseline levels exhibited modest cortisol increases in response to maternal singing; those with higher baseline levels exhibited modest reductions. These findings are consistent with the view that maternal singing modulates the arousal of prelinguistic infants.

Trainor LJ, Wu L, Tsang CD. Long-term memory for music: infants remember tempo and timbre.Developmental Science. 2004; 7(3): 289-296.
Study results show that infants’ long-term memory representations for melodies are not just reduced to the structural features of relative pitches and durations, but contain surface or performance tempo- and timbre-specific information.

Tramo M, Lense M, Van Ness C, Kagan J. Settle, M, Cronin, J. Effects of music on physiological and behavioral indices of acute pain and stress in premature infants: clinical trial and literature review. Music and Medicine. 2011; 3(2): 72–83.
This study examined the controlled use of recorded vocal music to attenuate physiological and behavioral responses to heel stick in 13 premature infants via an experimental design. Finds indicate controlled music stimulation to be a safe and effective way to ameliorate pain and stress in premature infants following heel sticks.

Tsang CD, Conrad NJ. Does the message matter? The effect of song type on infants’ pitch preferences for lullabies and playsongs. Infant Behav Dev. 2009; 33(1): 96–100.
Study results suggest that the overall pitch of a song is communicative to infants and that the affective nature of music can have an effect on infants’ pitch preferences. Moreover, infants’ preferences for pitch are context-dependent.