What term describes the rounding of lips during the entire production of a word like /bru/?

The term that describes the rounding of the lips during the entire production of a word like /bru/ is anticipatory coarticulation. This phenomenon occurs when a speech sound is influenced by a subsequent sound, leading to adjustments in articulation that prepare for the upcoming phonetic characteristics. In the case of /bru/, the /b/ sound is produced with rounded lips in anticipation of the rounded vowel /u/, which follows it. The rounding of the lips is carried throughout the production of the word, demonstrating how coarticulatory effects influence phonetic realization.

Anticipatory coarticulation is a common occurrence in speech production, where the articulators adjust in advance for the next sound in order to optimize the fluidity and efficiency of speech. This contrasts with other options, which do not pertain to the forward-looking adjustment that characterizes anticipatory coarticulation.