This study investigated the effects of three interventions -recorded mother's voice, white noise, and MiniMuffs, muffs used to attenuate environmental sounds- applied during a heel lance on pain and comfort in premature infants. This randomized controlled research was conducted in a state hospital tertiary-level neonatal intensive care unit. Sixty-four premature neonates with a gestational age of 31-36 who were stable, didn't receive mechanic ventilation and has been started feeding participated. The infants were randomly assigned to four groups: i) white noise , ii) recorded mother's voice, iii) MiniMuffs (earmuff), and iv) control. Five minutes before the procedure the white noise and mother's voice played and MiniMuffs placed on babies' ears. The heel lance procedure was recorded on a camera. The camera recordings were evaluated for premature infants' pain and comfort according to the Neonatal Infant Pain Scale (NIPS) and the Comfort behavior (COMFORTneo) scale.

Auditory interventions are commonly used during procedural analgesic administration in premature neonates. This study investigated the effects of three interventions -recorded mother's voice, white noise, and MiniMuffs, muffs used to attenuate environmental sounds- applied during a heel lance on pain and comfort in premature infants. This experimental study is a randomized controlled research. The data for the research were collected between September 2017 - April 2019. The sample comprised 64 premature infants with gestational ages of 31-36 weeks, who had been hospitalized at the Neonatal Intensive Cate Units (NICU). All infants in the study were in their first postnatal week. The study routine included a heel lance procedure to determine the level of bilirubin and hematocrit. The heel lance was performed with a lancet and the blood was transferred to the hematocrit pipette. All heel lances were conducted by the same nurse. Power analysis was conducted to determine the number of samples needed. Predicting that the NIPS score would decrease by 30-35% and decrease from 6 to 4-4.5 with 0.05 error and 80% power, the intervention groups yielded 64 infants divided into four groups of 16 as the target sample number. 80 infants included in the study, taking into account the loss of sample. Sixteen infants were excluded from the study. Sixty-four premature infants submitted for heel lance were evaluated.The randomization list was prepared by a third person using R version 3.1.3 package program and considering the gender factor. The list was concealed from the researcher and the family of the baby, and it was given to the researcher only during the procedure. The infants were randomly assigned to four groups. The infants were randomly assigned to four groups: i) white noise , ii) recorded mother's voice, iii) MiniMuffs, and iv) control. Five minutes before the procedure the white noise and mother's voice played and MiniMuffs placed on babies' ears. Heel lance procedures were recorded with a camera. Camera recording started before the procedure and continued until the baby stopped crying. The videos evaluated independently by two scientists (observers) who were specialists in neonatal services and pain. Observers evaluated infants' comfort, pain, and distress based on NIPS and COMFORTneo. In order to evaluate the agreement between the observers for the total scores of NIPS and COMFORTneo, pain estimation, and distress estimation, intraclass correlation coefficient were determined.

Inclusion Criteria:

• Born by cesarean section
• Non-supported by a mechanical ventilator or NCPAP
• Started to feed
• Within the first 10 days of postnatal

Exclusion Criteria:

• Had a major congenital malformation,
• Apgar score was less than 5 in the 1st-minute and less than 7 in the 5th-minute
• Received a sedative, muscle relaxant, corticosteroid, or analgesic therapy,
• First blood sampling attempt was unsuccessful
• MiniMuffs moved from their ears during the procedure
• Mothers who had problems recording their voice.

The data sharing plans for the current study are unknown and will be made available at a later date.

The infants were randomly assigned to four groups: i) white noise , ii) recorded mother's voice, iii) MiniMuffs, and iv) control. Masking could not be performed because the mother's voice was requested from the mothers.Masking could not be done because researchers and observers heard the mother's voice and white noise and saw the mimimuff.