Select a speech topic by considering the audience for the speech and your own personal knowledge and passions. Then find the intersection between the answers to these considerations to narrow down a speech topic.
Speakers should first think about the audience they are addressing. The demographics, beliefs, interests and attitudes of the crowd all play a huge role in how they receive a speech topic. An audience of seniors, for example, may not be engaged by a speech on trends in modern pop music, while a group of teenagers likely can't appreciate a speech on how to refinance a mortgage.
Next, speakers should consider what unique knowledge they possess. Generating a list of topics that you feel especially comfortable discussing. Next, go down the list and determine which topics you feel most passionate about, which ideas inspire the most enthusiasm, and which seem the most fruitful to address a specific audience.
Finally, speakers need to pull all of their ideas together and determine which topic best speaks to their own interests and the interests of the audience. While no single topic engrosses every audience member at every speaking event, considering all these factors helps determine a topic that engages a wide section of the crowd.