resulting prominence is often called accent rather than stress. There is considerable variation from language to language concerning the role of stress in identifying words or in interpreting grammar and syntax. Tempo Rhythm Although rhythm is not a prosodic variable in the way that pitch or loudness are, it is usual to treat a language's characteristic rhythm as a part of its prosodic phonology. It has often been asserted that languages exhibit regularity in the timing of successive units of speech, a regularity referred to as isochrony, and that every language may be assigned one of three rhythmical types: stress-timed (where the durations of the intervals between stressed syllables is relatively constant), syllable-timed (where the durations of successive syllables are relatively constant) and mora-timed (where the durations of successive morae are relatively constant). As explained in the isochrony article, this claim has not been supported by scientific evidence. Pause Voiced or unvoiced, the pause is a form of interruption to articulatory continuity such as an open or terminal juncture. Conversation analysis commonly notes pause length. Distinguishing auditory hesitation from silent pauses is one challenge. Contrasting junctures within and without word chunks can aid in identifying pauses. There are a variety of "filled" pause types. Formulaic language pause fillers include "Like", "Er" and "Uhm", and paralinguistic expressive respiratory pauses include the sigh and gasp. Although related to breathing, pauses may contain contrastive linguistic content, as in the periods between individual words in English advertising voice-over copy sometimes placed to denote high information content, e.g. "Quality. Service. Value." Chunking Pausing or its lack contributes to the perception of word groups, or chunks. Examples include the phrase, phraseme, constituent or interjection. Chunks commonly highlight lexical items or fixed expression idioms. Chunking prosody is present on any complete utterance and may correspond to a syntactic category, but not necessarily. The well-known English chunk "Know what I mean?" in common usage sounds like a single word ("No-wada-MEEN?") due to blurring or rushing the articulation of adjacent word syllables, thereby changing the potential open junctures between words into closed junctures. Cognitive aspects Intonation is said to have a number of perceptually significant functions in English and other languages, contributing to the recognition and comprehension of speech. Grammar It is believed that prosody assists listeners in parsing continuous speech and in the recognition of words, providing cues to syntactic structure, grammatical boundaries and sentence type. Boundaries between