Here is an example of an embedded audio file which you can play while hovering over a glossary item using the CM Tooltip glossary plugin for WordPress by CreativeMinds. The word mp3 includes an audio file, hover over it and click the play icon to listen to the audio
The CM Tooltip is a WordPress plugin that enables you to parse pages or posts that are used for showing defined glossary words or phrases. Generates an index page that contains the definition of the words used, synonyms and definitions from the Merriam-Websterdictionary or Wikipedia encyclopedia. When enabled, the plug-in displays an infotip that contains the definition of the highlighted word or phrase when the cursor hover-over the text. Also available in the WordPress Repository.