(Ubuntu) How to browse folder+subdirectories by filetype?

"Ubuntu also has a search tool like Windows. Under Places -> Search for Files you can choose what folder to search and a part of the filename to search for. You can even use regular expressions in the search (In the dropdown of Available Options, choose Matches regular expression). Unless you enjoy naming non-mp3 files weird things like myfile.mp3.txt, then using name contains should be sufficient for the search:

If you would like to use the command line:

find ~/Music -type f -name ""*.mp3"""