Late evoked responses to acoustic stimuli in relation to age.

Late hearing potentials (contigent negative variations; CNV) were studied in 66 subjects of different ages: 15 children, 26 adults and 25 elderly people (extreme ages of 4 and 100 years). Particular care was taken in selection of phonetic material suitable for each age. No CNVs were recorded in children under the age of 5 years; only 2 of the children examined presented late responses for all the phonetic lists. In adults, such cases rose to 5(19.2%), while another 16(61.5%) presented responses for some or a good part of the lists in question. Only in 9 elderly people were typical CNVs observed (36%). The discussion outlines the reasons for the low percentages of late responses obtained in children and point out that in some elderly subject accustomed to psychic and motor activities typical CNV are present.