This refinement of lip contact is also the first feeding movement that reaches a skilled level during nursing and early spoon feeding. By the time the infant reaches 6-9 months when babbling emerges and reaches its heights, precise lip movements are used to eliminate the loss of liquid during bottle or breast feeding, to remove food from the spoon, and to prepare the lower lip for cleaning by the teeth. The same level of skill has not developed for tongue movement. There is a gradual shift during this period toward tongue tip elevation. The independent upward movement of the tongue will not be seen for many months.
Sounds produced with the elevation of the back of the tongue develop around the same time period.
It may be necessary for the infant to perceive separate movements of the front and back of the tongue during feeding for this distinction to occur in sound production. These require movement patterns that are similar to those refined during the chewing process. These similarities do not prove that feeding skills are pre-requisite to talking. If this were the case, a child who is fed by tube would have no possibility of speaking. We know this is not true.