[header] How to help an autistic person develop voice prosody [title] Start with an assessment. [substeps] In this case, the assessment questions being a) how does the person speak now, and b) how does this impact communication and conversation? Select a team of highly observant people. These may include friends of the person, teachers, parents, support people and others. 
Have them record raw data on how the person speaks and how the person manages a conversation. If there are any incidental notes, include them separately from the data.