Experimental: Heart sound group

In the heart sound group, the heart sound with an average heart rate of 70 beats is transmitted to the loudspeaker via an Mp3 player. Two small 200 W loudspeakers (SONY®)/JBL brand loudspeakers are used, placed on either side of the newborn's head, 30 cm from the newborn's ears.

Experimental: White noise group

In the white noise group, the mother of the baby is told that the white noise to be used in the study will be used for pain relief. For the white noise, the musician Osman Orhan's colic album, which was released by the production and often used in the literature. The song Bebeğiniz Ağlamasın Pt-3 from the album Kolik will be used (permission to use it in this work has been granted by ON Music Production). The volume is set to 45 db. The JBL loudspeaker is placed on the newborn's toe 5 minutes before the procedure, about 30 cm from the newborn's ear, and white noise is played 5 minutes before, during (at the 1st minute) and 5 minutes after the administration of the Hep B vaccine.

No_intervention: Control

Newborns in the control group will not receive any intervention other than Hepatitis B vaccination.