It can also help convey emotion. Don't talk down. Because someone has a speech or hearing impediment does not mean the person's vocabulary is impaired. Speak in an age-appropriate manner. Don't avoid people with speech or hearing difficulties.
Many people avoid initiating conversations with people who have impairments out of embarrassment.
Remember that words are tools. Communicating comes from the heart and you might miss out on the conversation of your life if you shun those who are different from yourself.