In Taiwan, 183,254 newborns were born in 2018, with preterm births accounting for about 8-10%. The preterm infant required frequent medical treatment from birth to hospital discharge, which is accompanied by a painful process that can cause unstable vital signs in the short term and may affect their biological and psychological development in the long term. Music therapy is a non-invasive and easily accessible intervention, can be used to reduce the discomfort of painful stimulation during hospitalization of preterm infants. Music therapies in this text are the mother's voice and lullabies.

This study was a quantitative study of a randomized controlled trial, designed by experimental research method, and followed the principle of Allocation Concealment to conduct a randomized assignment trial. Using G*Power 3.1 to estimate the number of samples, and the statistical method chosen was Repeated measures ANOVA, the sample size is 120.

The subjects were divided into four groups, all four groups were administered general routine care, three experimental groups, and one control group, and the experimental group was a repetitive segment of audio recording edited to 13 minutes. There were three interventions: group A maternal voice reading children's books, group B lullaby, group C maternal voice reading children's books combined with lullaby, and the control group was the routine care group without any audio intervention. Physiological indicators, including heart rate, respiratory rate, oxygen saturation, and pain response assessed using the Neonatal Infant Pain Scale (NIPS), were recorded 3 minutes before, during, 1st, 3rd, and 10 minutes after heel lance puncture.

Inclusion Criteria:

1. Babies born alive before 37 weeks of pregnancy.
2. Infants who were required to receive heel lance procedure every 8 hours after physicians' diagnoses.
3. Those who can record the mother's voice and whose mother can read Chinese.

Exclusion Criteria:

1. Abnormal ear appearance, chromosomal abnormalities, congenital or acquired infections.
2. Postnatal patients whose mothers are not in the postnatal ward, e.g., those who need to be admitted to the intensive care unit due to their medical condition.
3. Patients used high-frequency oscillatory ventilators, because the high-frequency oscillatory ventilator gives 600 oscillatory breaths per minute and it is not possible to evaluate whether the study subjects can effectively listen to the interventions given, so they were excluded.
4. Mothers who were unable to complete the recording because of emotional ups and downs during the recording process.
5. Mothers who smoked, drank alcohol or used illegal drugs during pregnancy.
6. the patients was diagnosed with Asphyxia of the newborn at birth
7. Painkillers used within 2 days of birth.