Which is the most accurate definition of co-articulation?

• A. Articulatory changes that occur when one phone becomes similar to an adjacent phone.
• B. Articulators are moving to produce two different but overlapping sounds.
• C. Different articulatory gestures are used to achieve the same acoustic effects.
• D. Articulatory gestures are adjusted to require the least effort while maintaining intelligibility.

Answer: (B)

Co-articulation is the overlap of articulatory gestures in time as speech sounds are produced. In fluent speech, the movements of the lips, tongue, jaw, and other articulators don’t wait for one sound to finish before starting the next; they begin adjusting toward the upcoming sound while the current sound is still being formed. This simultaneous adjustment means the articulators are actively shaping two sounds at once, producing smooth transitions and influenced pronunciations across adjacent segments. That idea—articulators moving to produce two different but overlapping sounds—best captures co-articulation. The other notions describe related effects (like one sound becoming similar to its neighbor, or using different gestures for the same acoustics) or general tendencies (aiming for least effort), but they don’t define the overlapping, time-crossing nature that co-articulation embodies.