And what does the user do with the database after they start playing the audio file?
If they will be changing layouts, I'd use a floating document window with a container field in it to play the audio file.
If they are staying on the current layout, but making changes to data and changing records, I might use a global container field--but even then, there may be advantages to using a floating document window for this.
Does much more than you are trying to achieve - a $37 plugin
24U SimpleSound Plug-In enhances your FileMaker Pro solutions by allowing you to record and play your custom sound effects, spoken instructions, background music and other audio. It doesn't matter which operating system your clients use. You can play any sound format supported by QuickTime, such as WAV, AIFF, or even MP3. You can now simply turn your FileMaker Pro into a jukebox!
There is a YouTube video about it taken to an extreme