Does the movement of the lips affect speaking? The answer is No!
Words are primarily produced by the tongue. Please see the following figure.
You can see that the lips are not attached to the tongue. Therefore, there is no direct connection.
There is the orbicularis oris muscle, which is the soft tissue around the upper and lower lips, beside the platysma muscle, the buccinator muscle, the mentails, the depressor anguli oris muscle, the depressor labii inferioris muscle, the risorius, the zygomatic muscles, the levator anguli oris, the levator labii superioris and depressor septi nasi muscle.
These muscles move intricately, and the lips only articulate at the end of production.
The movement of the lips does not affect the speech or the ability to speaking smoothly.
In current research, we have found out that the movement of the suprahyoid muscles are the most important for speaking.
I previously described that there are no muscles that can move the larynx forward. Well, I’ve recently found out that this is not completely true.
If you can control the suprahyoid muscles smoothly, you can move the hyoid bone forward by using the genioglossus muscle.
I’m still investigating this fact and will keep you updated as the information develops.