In most cases. you'll know something about the audience you'll be addressing before stepping to the podium. If you're in an educational setting, consider the class you're speaking about as well as the age of your audience. If you're speaking to co-workers on budgetary matters in your office, hit any key points that need to be addressed. By first considering the audience, you'll winnow the speaking topics to relevant choices.
Music is a broad subject that relates to many people. Discuss musical history or break the topic even further by tracing the history of specific genres of music. If you're speaking to a younger audience, research the influence that jazz and rhythm and blues had on contemporary rock and roll.
A broad approach to history, to a lot of people, isn't an exciting topic for conversation. There are many fine points within the collective past, however, to choose from as a topic for a speech. Highlight a certain act of bravery from someone who served in World War II, the Gulf War or within Afghanistan or Pakistan. Discuss the importance of the Magna Carta and how it shaped the modern world. Consider your audience with any speech regarding history or historical events and make it relevant. You wouldn't discuss Victorian fashions with steam engine enthusiasts.
Famous people are a subject that an audience will find fascinating. Compare the importance of Michael Jordan's career with that of Babe Ruth's and how each affected how advertisers marketed their products to mainstream America. Examining Martin Luther's defiance against the Catholic Church may appeal to college-aged scholars.