Speech Sound Development
Speech Sounds as with all development are developed on a scale; meaning if your child has not mastered the /p/ sound by age three as should occur according to the speech sound developmental chart, there's no need to worry! First, all children develop sounds differently and master their sounds at different ages. Some children learn to master the /r/ sound at age three, while having difficulty mastering the /t/ or /d/ sound (just as an example to demonstrate that each child is to be treated individually and no child's development is alike. This chart is proposed as simply a diagnostic and guidance tool.
Speech Sound Developmental Scale