@demonhunter,
A speech/language pathologist would have screening tools to use with young children. A teacher would be able to identify an area of concern by using her trained ear as to what is developmentally appropriate or not, she would then consult with a speech path to do the screening. Speech ( articulation) in very young would not necessarily be as concerning as language difficulties. There is a lot of variation in the development of speech sounds. In later years articulation errors not corrected can cause a great deal of social stress as peers may make fun of the child, or not be able to understand him so avoid socializing with him. Early on the child can become frustrated and angry about not being understood. Cognitively articulation errors can show up in academic work in the areas of written work ( spelling). The earlier the remediation the better. Language is another issue. Difficulty developing language skills can greatly impact a child socially and cognitively. Obviously language is how we understand and process the world around us. It is the basis of all other learning. Socially even at a very young age language can interfere with understanding peers, and being understood. Although young children are very tolerant of differences amongst peers, they can still "give up" on trying to understand another child, or misunderstand their intentions. Depending on the temperament of the misunderstood child a lot of frustration can ensue, which can lead to behavior issues as well. Academic learning is VERY difficult for children with language problems. Think about the vocabulary, concept development, categorizing, comparing etc that goes into learning. A child can learn to read by rote but not understand what he has read, or do concrete math computation but not be able to apply those skills to higher order thinking. In my mind early intervention to remediate speech/language problems can help to prevent social acceptance issues, anger/behavioral issues, and learning issues at all levels of learning.