set of acoustically-defined distinctive features, which were supposed to correspond to auditory impressions of sounds. The pioneering publication was Jakobson, Fant and Halle (1951) Preliminaries to Speech Analysis (MIT). Grave/acute was defined primarily in acoustic terms (with some reference to auditory qualities), but sounds were given a secondary description (or gloss) in terms of their articulation. Features like grave/acute could be used to divide speech sounds into broad classes. For most phoneticians, the JF&H features had been superseded by 1968 by the articulatory features set out in Chomsky and Halle’s Sound Pattern of English and by competing articulatory features, which devised by Ladefoged in such publications as Preliminaries to Linguistic Phonetics (1971). References Jacobson, Roman; On Language. Harvard University Press, 1990 p. 260 Phonology