Rock and R & B after 1970. Pages 233-253.On the opening page, what did Stevie Wonder do to change the course of rock music as a business? (there's more information about Stevie Wonder on pages 242-243. )Explain how the business of rock changed, using the terms cross-marketing, album-oriented radio, and tape players. Elton John still makes a huge impact in the music world ( I saw him in concert November of 2017 ). What was his early influence in rock/pop music?Briefly explain rock music and the use of synthesizer, and groups that made an impact. Also tie in heavy metal. You may share about other groups not mentioned here. What is the Philadalphia sound, and who was important in engineering that?Define the singer-songwriter, and a few musicians in that genre. Define glam rock, and the key musician associated with that. The art of recording is given to the best engineered album. Explain this and the group who mastered this technique. Name a music piece from our listening