The effect of gender on one-day-old infants' behavior and heart rate responses to music decibel level.

The purpose of this study was to examine gender differences among full term infants' responses to music played at a range of decibel levels. These responses were measured by physiological data (heart rate) and behavioral data (behavior state score). All subjects (N = 36) were healthy, 24-48 hours old, and had passed a hearing screening at the time of testing. Heart rate and behavior state were recorded as male (n = 18) and female (n = 18) subjects listened to alternating 3-minute periods of silence and music for 21 minutes. The music--an excerpt of an instrumental lullaby--was presented via small speakers placed on either side of each subject's head and played at three different loudness levels: 55-60 dB, 65-70 dB, and 75-80 dB. Heart rate was measured using a pulse oximeter with a Y-sensor attached to each subject's great toe, and behavior state was measured using a scale adapted from the Neonatal Behavioral Assessment Scale (Brazelton & Nugent, 1995). A two-way analysis of variance with repeated measures computed for both order and gender found no significant difference in heart rate or behavior state during the three loudness levels. Possible reasons for this lack of difference include enjoyment of the music regardless of intensity or physical inability to discriminate between the different levels.