As a long time emacs user, it's great to know that it can grow to support new languages and environments. I wasn't aware that it supports Octave (the music language). Welcome to emacs, we hope you enjoy your stay!
One of my favorite things in emacs. When confronted with an arcane, custom "language" developed 30 years ago because of some immediate need without serious care taken. You can create a custom mode that gives you syntax highlighting, indentation support and other things fairly quickly. And it beats the built-in "editors" present in a lot of tools, especially those that don't let you directly edit the text file but insist on making you click through wizards and dropdown menus.
This sort of thing is where I've found emacs most valuable. For proprietary or product-specific configuration and scripting languages, particularly ones where no decent editor is provided at all (or there's some terrible builtin editor, based on SciTE at the very best), being able to quickly put together an emacs major mode is very handy.
Once you've got the basics written, you can start to work. Then add imenu support, and you have file browsing. Then add your language to exuberant ctags - which has a line-based regexp mode that you can pretty much reuse your imenu regexps for - and get it to generate emacs-compatible tags files, and you've got basic cross-file symbol navigation.
(The quality of ctags-based symbol browsing can be hit or miss - for languages like Java or C++, where many mechanisms require symbols to be identically-named, it's not that great. But not-that-great is still a lot more convenient than nothing.)
I can't find "octave music language" anywhere on Google either. But maybe the commentor was thinking of abc-mode and misspoke? That one is for a music language.
