After you have decided upon a broad topic for your speech, there are several strategies that will aid you immensely in narrowing your focus. By taking the time to explore and narrow your subject before jumping immediately into a massive literature search your search will be more precise and you will save time in the long run.
Browsing the Library. A good way to narrow your topic is to browse the library stacks. The University of Tennessee library uses the Library of Congress Classification (LCC) system to organize books on the shelves according to unique call numbers. LCC call numbers consist of two letters followed by a string of numbers and letters. For browsing, all you have to remember are the first one or two letters. These letters represent broad disciplines or classes within the LCC schedule. The letters BF, for example, represent the discipline of Psychology. The range of numbers following the letters in a book's call number indicates a subclass. For example, if you wanted to find more information about Cognitive Psychology use the schedule to find a subclass. The call numbers BF309 - BF 499 contain books in the Cognitive Psychology subclass. By familiarizing yourself with the broad classification letters for your field of study, as well as the number ranges for important subtopics you can save time when you go to the library to begin researching.
Identify Key Concepts for your Search. Another useful way to narrow a speech topic is to identify the Library of Congress Subject Headings (LCSHs) associated with the topic. Subject headings can be used to search the library catalog, online databases, or the internet. LCSHs are assigned to books to describe their content and allow for easier access.