What articulatory movement is associated with enlarging the oral cavity?

Enlarging the oral cavity primarily involves actions that create more space within the mouth. Pursing or rounding the lips serves as a key movement in controlling how the oral cavity shapes sound, especially during speech production. When the lips are rounded, they can significantly alter the resonance of the vocal tract, leading to different sounds.

This action helps in creating a larger, more open environment for sound to resonate, facilitating specific acoustic properties necessary for certain phonetic outputs. In contrast, other movements, such as flattening the tongue or raising its tip, primarily adjust the shape and position of the tongue rather than the overall volume of the oral cavity. Lowering the jaw does create a larger area, but it is not as direct in the context of speech as rounding the lips in relation to specific speech sounds.