One of the things in the list last time about early clues to Dyspraxia was a child not being able to modulate their voice. Or they may appear to on occassion when the voice just happens to come out quieter - maybe they are sleepy or tired.
It really doesn't help for adult to tell the child to sssshh. That actually means stop and be quiet. But we want them to learn to speak quieter not stop! Maybe the adult says to speak quieter, but how does the child know what this means. This is the key question and means that the child needs to learn to listen to themselves first of all. They need to learn that sound comes in different levels.
A great way to do this is by singing. Have fun at the same time too. Choose a song the child likes and sing it very loudly, then very quietly. Tell the child "Let's sing loudly/quietly." Before you begin the song. No whispering though, because whispering is totally different in the way the voice box is used.
Once they can sing loudly and quietly, then you can move onto graduating the level of loudness. With singing very loudly, a little bit quieter, a little bit quieter, very quiet, etc.
Later on you can do this same exercise with sounds - animal sounds, vehicle noises, fun sounds.
And you can encourage them to notice environmental sounds and how loud they are.
Once they have learned to modulate their voice in this way, then you can tell them about speaking. So sometimes tell them that you are speaking very loudly, loudly, or quieter etc. And this leads into being able to ask them to speak louder, or quieter.
Make sure you give them attention and listen to them when they are speaking quieter though, otherwise the child may speak louder to get your attention.