Naatanen, Risto; Anne Lehtokoski, Mietta Lennes, Marie Cheour, and others (1997).
Language-specific phoneme representations revealed by electric and magnetic brain responses
Nature 385 (6615): 432 (3 pages).

Abstract: It has been proposed that early processing of sounds depends on whether these sounds form part of speech. This speech specificity hypothesis suggests the existence of language-dependent memory traces that go into action when speech is processed, but not when complex acoustic non-speech stimuli are processed. The presence of such traces in the human brain is examined using the Finnish phoneme prototype /e/ as the frequent stimulus and the Estonian prototype /o/ as the infrequent stimulus. Cortical memory of speech sounds were found, providing support for the speech specificity postulate.