A Dictionary of Linguistics and Phonetics David Crystal

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forms is a dummy auxiliary, which carries the tense/number contrast for the
verb phrase (do/did you know, do/does he know). Notions involving zero
(e.g. ‘zero morpheme’) could also be considered types of dummy. In transformational
grammar, dummy symbols are sometimes introduced into the deep
structure of a sentence, to facilitate the derivation of classes of sentence,
but they never appear in the sentence’s surface structure, e.g. the various kinds
of boundary symbol, or the delta (∆) symbol which acts as a ‘place-holder’
for lexical items (specified as complex symbols). In government-binding
theory, the term refers to elements in A-position (usually in subject position)
with no theta role; they are also known as ‘expletives’.
duplex perception An experimental technique used in auditory phonetics
involving the manipulation of two components of a sound stimulus, one in each
ear. In one ear, listeners are presented with a synthesized stop+vowel syllable
(such as [ìa]) from which the second or third formant transition has been
removed; this transition formant is simultaneously presented to the other ear.
People typically perceive a complete [ìa] as well as the isolated transition, which
sounds like a non-speech ‘chirp’. The perception is said to be ‘duplex’ because of
the double effect: listeners hear both the integrated percept and the isolated
transition percept.
duration (n.) A term used in phonetics, to refer to the length of time involved
in the articulation of a sound or syllable. Distinctions between relatively
‘long’ and relatively ‘short’ durations are measured in units of time, such as the
millisecond (msec). In speech, the absolute duration of sounds is dependent to a
considerable extent on the overall tempo of speaking. Issues which need reference
to duration include the study of rhythm (see isochrony), consonant
articulation (see voice-onset time), and juncture.
durative (adj./n.) (dur, DUR) A term used in the grammatical analysis of
aspect, to refer to an event involving a period of time (see continuous, progressive);
it contrasts with ‘non-durative’ or punctual. A verb-form is said to
express ‘durative meaning’, or durativity.
dvandva (adj.) In grammar, a Sanskrit term describing a type of compound
where the elements exist in a co-ordinate relationship (see co-ordination),
lacking any internal dependency; also called a copulative compound. Examples
include the Franco-German pact and the London-Edinburgh express, as well as
extended structures such as Polonius’s tragical-comical-historical-pastoral (Hamlet
II.ii.396).
dyadic (adj.)
see valency
dynamic (adj.) (1) A term used in grammatical classification, referring to one
of the two main aspectual categories of verb use; the other is stative or
static. The distinguishing criteria are mainly syntactic; for example, dynamic
verbs occur in the progressive form (e.g. I’m running, He’s playing) and in the
imperative (e.g. Run!). The semantics of this class covers a wide range, including
activity, process (e.g. change, grow), bodily sensation (e.g. feel, hurt), etc.