We say that a linguistic entity is prosodically prominent when it stands out from its environment by virtue of its prosodic characteristics. That is, we define prominence as a property of a linguistic entity relative to an entity or a set of entities in its environment. Although the definition is cast in relative terms, it includes monosyllabic utterances, because they stand out from silence. In the acoustic domain, the primary prosodic properties bringing about these relative differences are amplitude, duration and ‘F0’ (we use F0 as a shorthand form for the inverse of the quasi-periodicity of the speech signal). The corresponding perceptual properties are loudness, duration or length, and pitch. Also, particular aspects of timbre come into play, such as those relating to vowel reduction, spectral slope or tilt, etc., and properties relating to voice quality, e.g. creak.