Music soothes, and the existence of the lullaby is presumptive evidence that mothers have always, or nearly always, believed that it can quieten babies. For over a quarter of a century evidence has accumulated that music might improve the physiological responses and growth of premature infants. Such infants are often subjected to levels of noise which cause concern but the special properties of music may make it beneficial. A meta-analysis ( Jayne M Standley. Journal of Pediatric Nursing2002;17:107–13OpenUrlCrossRefPubMed ) has given support to the view that music is good for premature infants.

Ten studies met predetermined inclusion criteria. (The meta-analyst was author or co-author of six of these studies.) Six studies used recorded, free-field music, usually lullabies, three used recorded music through earphones, and one used live singing. Music at 55 to 80 dB was associated with improvements in behavioural state, heart rate, respiratory rate, oxygen saturation, weight gain, feeding rate, non-nutritive sucking rate, and duration of stay in hospital.

The author of this meta-analysis recommends lightly rhythmic music with unaccompanied voice or voice plus one instrument, constant rhythm and volume (low seventies dB), and no more than 1.5 hours per day, alternating 30 minutes on with 30 minutes off. Live singing of lullabies she regards as excellent but she definitely disapproves of music-generating toys or mobiles.