And then it has a detailed paragraph for each item on that list, but looking at the list you can get an idea of what you're looking for if you're testing a vocal part. All of this is stuff you'd be looking at in-game (no Reaper required) and some of it you can even check outside of the game (lyrics are displayed on each song's page on the site). One limitation of Audition Mode is that you can't "rewind" or "skip back" so if you need to hear/look at something again, you have to restart the song. Hopefully they'll update it at some point to add that feature.
* Are all note tubes the same pitch as what the vocalist is singing?
* Do note tubes last the correct length?
* Is each note tube tied to a single syllable?
* Are all non-pitched lyrics authored as talkies? Is it possible to hit them and get an "awesome" rating?
* Are all lyrics spelled correctly?
* Do all of the lyrics match up to what the singer is singing?
* Are there any hyphens appearing in places they shouldn't?
* Does each phrase begin with a capital letter?
* Are all of the phrases a reasonable length? Do all of the lyrics of each phrase fit on the screen in the static HUD?
* Are all overdrive phrases in the song usable?
* Is the vocalist animating properly?
* If applicable, do the percussive sections of the song make sense in the context of the song? Are the phrases an acceptable length?