This study attempts to evaluate procedures for studying hemispheric differences in newborn human infants and to determine what acoustic characteristics of speech sounds will trigger a left hemisphere (LH) repsonse. Within 48 hours of birth, 14 neonates were individually administered five aural stimuli which comprised two speech syllables, two nonspeech stimuli, and a 500 Hz tone. These stimuli were presented individually to the infants, and corresponding auditory evoked potentials (AEP) were measured by means of recording electrodes on left and right temporal areas of the infant's brain. Factor analysis was used to isolate the minimum number of AEP components which accounted for the majority of the variance. Four factors were found which together accounted for 96% of the variance. The results offer further evidence to support the idea that hemispheric differences are present during early infancy and that there are AEP differences between male and female infants. Although the study failed to demonstrate acoustic factors which trigger differential hemishperic responding, discrete components of the AEP responses were identified which were responsive to specific aspects of the acoustic stimuli. Information concerning temporal differences in the processing of these elements was also obtained. (GO)