One of the most important tasks that humans face is communication in complex, noisy acoustic environments. In this chapter, the focus is on populations of children and adult listeners who suffer from hearing loss and are fitted with cochlear implants (CIs) and/or hearing aids (HAs) in order to hear. The clinical trend is to provide patients with the ability to hear in both ears. This trend to stimulate patients in both ears has stemmed from decades of research with normal-hearing (NH) listeners, demonstrating the importance of binaural and spatial cues for segregating multiple sound sources. There are important effects due to the type of stimuli used, testing parameters, and auditory task utilized. The review of research in hearing impaired populations notes auditory cues that are potentially available to users of CIs and HAs. In addition, there is discussion of limitations resulting from the ways that devices handle auditory cues, auditory deprivation, and other factors that are inherently problematic for these patients.