Learners who use incorrect rhythm patterns or who do not connect words together are at best frustrating to the native-speaking listener; more seriously, if these learners use improper intonation contours, they can be perceived as abrupt, or even rude, and if the stress and rhythm patterns are too nonnative like, the speakers who produce them may not be understood at all.

(Celce-Murcia et al., 1996, p. 131)

Stress, rhythm, and adjustments in connected speech can be easily overlooked in the language classroom. Nonetheless, these invisible signals are among the main clues used by listeners to process incoming speech and are thus of primary importance in the speech communication process.

Celce-Murcia et al., 1996, p. 172)