Auditory processing disorders contribute to communication difficulties in children with language-based learning impairments and in older adults who have trouble hearing in background noise. Therefore, deficits in auditory processing are widespread among these diverse populations. For this reason, it behooves both scientific and clinical communities to consider optimum techniques for assessing and managing these deficits. The auditory brainstem response to complex sounds (cABR) provides an objective index of the biological health of the central auditory system. The cABR is also a sensitive indicator of training-induced neuroplastic changes and can therefore be used to assess treatment efficacy. Once integrated into clinical practice, use of the cABR may facilitate more widespread evaluation and treatment of auditory processing disorders.