The purpose of a warm-up is to remind yourself how to sing what you need to sing today. A warm-up will not improve your singing much - you use a workout to do that - but it gets you ready for singing well today.
Here is one warm-up technique that covers everything in few as 2 minutes when you're in good voice and health to 20 minutes when you're ill with vocal trouble. Do a warm-up everyday, whether you are doing a performance, rehearsal, practice, or nothing at all that day.
The Daily 7-Minute Vocal Warmup
WARNING: DO NOT USE THIS WARM-UP WHILE DRIVING. You safety depends on your attention to the road - do not distract yourself. Do this when you can concentrate on it without putting yourself in danger, please.
Part One: Stretches.If you've already been active today and feel limber and relaxed, skip these physical stretches.
Basic rules for physical stretches: (quoting Dummies.com [with a few comments])
Move into each stretching position slowly. Never force yourself into a stretch by jerking or snapping into position.
Notice how much tension you feel. A stretch should rate anywhere from mild tension to the edge of discomfort on your pain meter. It should never cause severe or sharp pain anywhere else in your body. [Hold stretches while you relax into the stretch.] Focus on the area you’re stretching, and notice the stretch spread through these muscles. [Relax.]
As you hold each position, take at least two deep breaths. Deep breathing promotes relaxation. [And breathing is the base of singing]
Never bounce. After you find the most comfortable stretch position, stay there or gradually deepen the stretch. Bouncing only tightens your muscle — it doesn’t loosen it. Forceful bouncing increases the risk of tearing a muscle.
2. Head: (roll standing or sitting) point your chin every direction: up, left, down, right. Repeat.
3. Jaw : Open mouth and eyes wide. Squint and make a sour face. Repeat.
4. Shoulder: roll up, back, down, forward. Repeat
5. If you like or need it, self-massage your face, jaw and throat or anywhere else you carry tension.
Part Two: Core Sound.Your core sound is beautiful mid-range singing, with little strain. The more you sing, the more free and beautiful your core gets. When ill, even the core sounds poor, but that's what you start with in a warm-up and build from there.
1. Yawn-sigh: yawn, inhale and sing a sigh from the top of your range to the bottom, then bottom to top on "ah", easy and light.
2. Find any Core sound, a pitch you can sing well right now, that feels easy and sounds loud and beautiful. "mm", "oo" or "ah" are likely vowels, and most folks find a core around G or f, but it doesn't matter what pitch you find, only that you find a core sound now.
3. Long Tone: take a good deep, low breath and sing that core note for 15 seconds on the clock. If you can't make 15 seconds, focus on breath technique and try again.
Part Three: Range.Take that core sound to the extremes you need today: high and low, loud and soft, open and closed.
1. Sirens low and high: Starting from your core sound, slide the note low and hold it. Then start from core, slide it high and hold that. While doing these sirens, change as little of the vowel and placement as possible, keeping and stretching your beautiful core sound
2. Scales low and high: Using any instrument, locate your core pitch. (If you haven't an instrument, just make your best guess and continue:) Sing scales to the notes you need. Here are typical ranges for choristers, and which scales to sing from typical core notes.
|Vocal part||typical core||low note||interval down||high note||interval up|
|Bass||E||E'||octave down||d||octave up|
|Baritone||F||G'||octave down||f||octave up|
|Tenor||G||B'||fifth down||a||octave up|
|Alto||f||F||octave down||e'||octave up|
|Mezzo||g||A||octave down||g'||octave up|
|Soprano||a||c||fifth down||a'||octave up|
You can and should extend or shorten the scales to match the notes you need. If you sound easy, loud and beautiful on your scales, great. If not, try them once or twice again. Doing more scales than three is fine, and now they're a workout and practice.
3. Specials: if the music you're singing has tricky vowels, speed, diction, or dynamics, simply sing the tricky music about as well as you did it last time you sang it. You can attempt it many times and even turn this into practice and work with any of the hundreds of vocal exercises and learning tricks that exist, but...
When you achieve the object of the warm up (remind yourself how to sing), you're ready.