When saying words our mouth is always ready for the next sound to be made. While saying one sound, the lips, tongue, etc., are starting to form the sound to follow. This can distort individual sounds during speech because the sounds are not produced in isolated units (e.g., ham- the /m/ blends with the /a/ to distort the vowel). This process is called coarticulation. Because of coarticulation, some children have difficulty hearing the individual sounds in words and the concept of phonemes needs to be explicitly brought to their attention through instruction.