Fluency can be defined in part by prosody, which is shown graphically by a smooth intonation contour, and by a number of other elements: control of speech rate, relative timing of stressed and unstressed syllables, changes in amplitude, and changes in fundamental frequency.
Revised Hierarchical Model, developed by Kroll and Stewart, is a model suggesting that bilingual brains store meanings in a common place, word-forms are separated by language [REF].