II.  DEVELOPMENTAL LANGUAGE  DISORDER 7.  Language, the Auditory System, and Maturation The capacity for language depends upon connections within the temporal and frontal lobes, but what guides maturation of the cortical language circuits? Language is learned through the auditory sense. Auditory dysfunction is evident in children with autism, both in hyper-reactivity to some sounds as well as inappropriate obliviousness to others. 2 - Research with radio-isotope tracers The auditory system is metabolically more active  than any other area of the brain. 3 - Hearing, attention, and degrees of deafness Deafness in childhood requires special education for language learning, and must be recognized as a disability - not just a human variant. Hearing loss in old age often involves difficulty following conversations in a noisy environment, and also often to withdrawal from social interactions. Auditory impairment in a child with autism should be investigated as possibly similar to that of the elderly, or at least that of an adolescent past the critical age of being able to master a new language "by ear" and without a foreign accent. 4 - Early maturation and stimulation of cortical growth The auditory pathway is myelinated and functional by 29 weeks of gestation. Early maturation of brainstem pathways should be viewed as possibly important in stimulating growth of later developing areas of the cerebral cortex. 5 - Metabolic rank order The inferior colliculus is the most metabolically active structure in the brain.