The goal of this clinical study is to test a new, novel medical device designed to improve speech sound differentiation among hospitalized preterm infants. The device is designed to be used at an age equivalent to 32 weeks of gestation or older and to integrate readily into clinical practice for use by nurses and therapists staffing Level II to Level IV NICUs. Preterm born infants are at high risk for neurosensory impairments and developmental delays. In the NICU, infants are often deprived of infant-directed parental speech because of numerous challenges to parental visitation, resulting in reduced differentiation of speech sounds, altered brain structure and poor language outcomes. The study will explore the effectiveness of a novel medical device designed for infant learning through contingent sucking on a pacifier equipped with a sensor for suck pressure/timing, connected to a speaker that delivers mother's voice. The study will test the hypothesis that there will be a greater response difference between speech sounds on EEG, for infants receiving the suck-contingent mother's voice intervention than for infants hearing the same amount of non-contingent mother's voice from a speaker device.