This clinical study aims to evaluate how two types of gentle sounds - white noise and a traditional Turkish lullaby ("Dandini Dandini Dastana") - affect the vital signs of term newborns cared for in the Neonatal Intensive Care Unit (NICU).

The first weeks of life are critical for newborns, especially those who need special care in the NICU. During this time, maintaining physiological stability-such as normal heart rate, breathing rate, and oxygen levels-is essential. In addition to medical treatments, non-pharmacological interventions like music and soothing sounds are increasingly used to reduce stress and support comfort.

In this randomized controlled study, 70 term newborns (born after 37 weeks of gestation and weighing at least 2500 grams) were randomly assigned to one of two groups:

• White Noise Group: infants listened to a digitally recorded white noise (imitating intrauterine sound patterns) for 20 minutes.
• Lullaby Group: infants listened to a recording of the traditional lullaby "Dandini Dandini Dastana" for the same duration.

Both interventions were administered three times a day for four consecutive days in a calm NICU environment. The sound level was carefully calibrated not to exceed 55 decibels (dBA), ensuring safety for newborn hearing.

Researchers measured heart rate, respiratory rate, and oxygen saturation (SpO₂) at baseline and at the 5th, 10th, 15th, and 20th minutes during each session.

Results showed that both white noise and lullaby sessions led to a gradual decrease in heart rate, while breathing rate and oxygen levels remained stable. No adverse events or signs of physiological instability were observed.

These findings suggest that both white noise and lullaby listening are safe, low-cost, and effective supportive methods for helping term newborns remain calm and physiologically stable during intensive care. The study contributes to growing evidence that structured auditory stimulation can help promote comfort and self-regulation in newborns without the need for medication.

Background and Rationale: Newborns admitted to the Neonatal Intensive Care Unit (NICU) are frequently exposed to environmental stressors that may disrupt autonomic stability. Developmental care strategies increasingly incorporate sensory modulation approaches to support physiological regulation. Auditory stimulation, including white noise and lullabies, has shown potential to reduce stress responses and promote behavioral organization. However, comparative evidence in term newborns remains limited, as most studies have focused on preterm populations. This study was designed to evaluate and compare the short-term physiological effects of two standardized auditory interventions-white noise and lullaby exposure-in term newborns under controlled NICU conditions.

Study Design and Setting: This was a prospective, multicenter, parallel-group randomized controlled trial conducted in two tertiary NICUs in Türkiye. Participants were randomized in a 1:1 ratio using stratified block randomization by center, with allocation concealment ensured through sealed opaque envelopes.

Intervention Protocols: Both interventions were delivered in a standardized manner to minimize environmental variability. Auditory stimulation sessions lasted 20 minutes and were administered three times daily over four consecutive days. Sound intensity was calibrated prior to each session and maintained below 55 dBA to ensure auditory safety. White noise exposure consisted of a digitally standardized recording simulating intrauterine acoustic patterns. The lullaby intervention consisted of a culturally familiar, standardized digital recording. All sessions were conducted during stable clinical conditions and scheduled to avoid routine caregiving activities. The playback device was a portable MP3 player with a 3-5 W speaker placed approximately 50 cm from the infant's ear. Sound intensity was measured before each session using a Wintact WT85 decibel meter, maintaining a maximum of 55 dBA (A-weighted). Sessions were conducted during quiet periods after routine care and feeding to minimize external stressors.

Data Collection and Measurements: Physiological parameters were obtained using continuous bedside monitoring systems. Heart rate and oxygen saturation were automatically recorded, while respiratory rate was assessed using standardized observation methods. Repeated measurements within sessions enabled evaluation of temporal trends and within-subject variability.

Statistical Analysis: The primary analytical approach utilized linear mixed-effects models to account for repeated measurements within individuals. Fixed effects included intervention group, time, and group-by-time interaction, while random intercepts accounted for within-subject correlation. Baseline values and study center were included as covariates. Sensitivity analyses were performed to assess the robustness of the findings.

Ethical Considerations: The study was approved by the institutional ethics committee, and written informed consent was obtained from parents or legal guardians prior to enrollment. All procedures were conducted in accordance with the Declaration of Helsinki.

Inclusion Criteria:

• Gestational age ≥ 37 completed weeks
• Birth weight ≥ 2500 grams
• Postnatal age between 0 and 28 days at enrollment
• Admitted to the neonatal intensive care unit (NICU) for any medical reason
• Spontaneous breathing (not intubated)
• No current sedative or analgesic medication
• Written informed consent obtained from parents or legal guardians

Exclusion Criteria:

• Gestational age < 37 weeks (preterm infants)
• Birth weight < 2500 grams
• Congenital hearing loss or major congenital anomaly
• History of seizures or intracranial hemorrhage
• Requirement for mechanical ventilation
• Current use of sedative or analgesic drugs
• Early discharge or death before completion of the intervention protocol
• Parental refusal or withdrawal of consent during study procedures

Individual participant data (IPD) will not be shared due to the inclusion of neonatal participants and the sensitive nature of clinical data collected in intensive care settings. Only aggregated, de-identified summary data will be reported in publications and conference presentations. Data sharing beyond these summaries is restricted by institutional ethics approval and parental consent limitations.

Due to the nature of the auditory interventions, participants and care providers were not blinded. However, physiological data (heart rate, respiratory rate, SpO₂) were extracted automatically from monitor systems and analyzed using group-coded datasets (Group A / Group B). The outcome assessor and statistician remained blinded until the completion of data analysis.