"vocalize" is a lot of things:

First and foremost, it's a song about writing a song. For many songwriters, composing allows them to "vocalize" their innermost thoughts and feelings.

This ties into the song's second function: my take on Miku Hatsune. For me, Miku expresses the ability to take an idea and share it with the world. She's a voice for those who may not have one. When you think about it, a song like this seems right up her alley, huh?

Think of it like Miku and I trying to encourage you into not just writing a song, but stepping out into the world and sharing what kind of amazing person you can be. That's what "vocalize" is supposed to be.