Just one of the perfect warm-ups!

            Brahms' "Four Serious Songs" (Vier ernste gesange) entirely on a hum (closed mouth and relaxed) is the perfect warm-up for the voice.

Works on following:

• phrasing (A LOT!!), 
• definitely connection of the breath (management and control), 
• onset and offset (still more breath connection), 
• tension (these areas are immediately recognized and can be addressed with relaxation techniques and correct breath onset, etc), 
• pitch (you can really tell which sections need to be lifted more and need a more energized breath flow and raised palate), 
• characterization (this goes back to phrasing but you can really focus on the intended character with just the music). 

The addition of text (with correct diction and articulation) will make this even more profound). I'm sure I'm forgetting something but I'm typing this simultaneously as I hum with Brahms (hehe).

Source: http://www.youtube.com/watch?v=AQgd7M3BJdg

Thanks for reading!