Speech is a multi-faceted skill but the actual production of words requires fine control and coordination of muscles running down the midline of the face and neck, the tongue, laryinx, facial and throat muscles.
The midline of the body is potentially the most complicated 'zone' for the brain. For instance, we can confuse vision in the brain by simply inducing double-vision by staring at something in the midline of our vision. This is caused because the image is processed through both the left and right eyes and 'seen' in both the opposite brain hemispheres. Because each hemisphere is seeing the same image, it can struggle to overlap to produce one image. Under these conditions we often see both, or as we call it, double vision.
Even hearing can be difficult if it comes directly to our midline. Very often we will turn our head slightly so our dominant ear is positioned towards the midline. With speech we may not perceive the difficulties in the co-ordination of the muscles in the same way as we do with our sensory systems, but it can still be as complicated for the brain.
Using movement programmes that develop the co-ordination of the left and right sides of the body and left and right motor areas in the brain can have a role in enhancing the ability to produce speech. Exercises that build strength and agility in the facial muscles are also beneficial.