The way Android works is that when you start (or restart) it, it scans the phone for media files, then builds a database of files, where they are and what the type (mp3, mp4, jpg, etc.) is. Then media apps look in the database for filetypes they can handle, and list them for you. An mp3 file is an mp3 file, whether it's an orchestra performance or a TED talk.
As B. Diddy said, if you build a playlist of your music files, and you have an app that can use a playlist, you'll only see the files on the playlist when you're looking at it.
(An interesting modification to Android would allow the user to tag media files as voice, music, TED, etc. The same for videos - personal, movies, etc. And let apps give you a menu choice of what tag you want it to handle this time. Not that Google ever listens to me - I was asking for the a/b system for years before they finally implemented it. [Tech support still has no idea what it is or how to use it to recover from a corrupt update.])