Vocal Jazz Techniques
It is not essential to have an amazing vocal range or technique to sing jazz, which makes it great if you've never sung before. Singing jazz standards is about exploring the unique qualities of your voice and learning how to personalise a song. Your jazz singing voice should be a natural extension of your speaking voice.
The best way to begin is by immersing yourself in the music of the great singers. Some of the best females include Billie Holiday, Ella Fitzgerald, Sarah Vaughan, Carmen McRae, Betty Carter and Peggy Lee. Male jazz singers to listen to include Nat King Cole, Frank Sinatra, Mel Tormé, Louis Armstrong, Joe Williams, Tony Bennett, Jon Hendricks and Mark Murphy.
Microphones
The evolution of jazz singing owes a lot to the development of the microphone. Mics have made it possible to do all kinds of subtle things vocally, such as whispering or singing in a breathy way. You might want to purchase a portable PA and microphone, which will make your voice sound very different. As you become more advanced, you will need to build a relationship with your amplified voice. You should also purchase a means of recording yourself, because at some point you should refrain from listening to other singers and listen closely to your own voice. Once you're comfortable with the sound of your voice through a mic, look for opportunities to sing at vocal jazz workshops and open mic sessions with accompaniment.
Songbooks
Buy a songbook, preferably one containing tunes from the "great American songbook" - the standard repertoire of most jazz singers which includes the songs of Jerome Kern, Irving Berlin, George Gershwin and Cole Porter, among others. There are broadly two formats: sheet music with piano accompaniment, or Real Books, which contain just the melodic line and chord symbols. Jazz musicians generally prefer to work from Real Books since it opens the way to a freer form of accompaniment.
Key
When learning any song it is essential that you find a key (or register) that is comfortable for you to sing in. One good way to do this is to begin by singing a song freely, away from the music. Experiment with different registers, and then go to a piano or guitar to work out which key you are singing in. One tip here: the key you are singing in may not be the same as the note you start on, but it may well be the note you finish on. Once you know your key for a particular song, remember it for future reference. That way, if an accompanist ever asks you which song you want to sing, you'll also be able to name the key you'd prefer to sing it in. You will then need to produce a song sheet, in your desired key, for both yourself and your accompanist.
Transposing songs is tricky if you have no knowledge of music theory, but help is available. You can buy a music program such as Band in Box or Sibelius - simply enter the melody and chords found in your Real Book and the computer will transpose the part into your key. Alternatively, you could track down a jazz musician who can transpose and produce some arrangements, or "charts", for you.
Lyrics and melody
You now need to learn the lyrics and melody of a well-chosen standard. Beginning with the lyrics, it is a good idea to memorise them as if they were a poem. After all, your aim is to move an audience by conveying the lyrics of a song as if it were a poem set to music. When memorising lyrics, read them out loud, remembering to stress the important words. For example, in the song All of You by Cole Porter, the opening line is "I love the look of you". You should stress the words "love", "look" and "you" to convey the meaning of the phrase; this added definition brings the lyrics to life.
Now put the lyrics aside and look at the melody. Begin by singing the melodic line to "la-la-la" or "do-bi-do" with clear diction and good intonation. A more advanced exercise is to sing only on the vowels, so "Summertime" would become "u-er-i". This draws attention to the many "colours" in your voice. Now sing your song from memory, exactly as it was originally written by the songwriter. It is important that you don't fall into the trap of only being able to sing a song as interpreted by, say, Ella Fitzgerald.
Rhythmic displacement
The freedom to loosen up the rhythm of a song spontaneously to add intensity is one of the joys of singing jazz. To practise rhythmic displacement, it is a good idea to begin by learning a simple ballad, such as Embraceable You by George and Ira Gershwin. Having memorised the song, start subtly "loosening up" the timing of each phrase. The idea here is to sing the words rather like you might say them. Try shortening and lengthening different notes each time you sing a phrase and notice how playing about with the rhythm changes the emphasis on the words and can help you put your own stamp on a song. Your singing will also sound more like jazz if you leave a short space (about the length of a clap) before launching into every phrase.
Swing
The other fundamental aspect of jazz singing is being able to swing. To get into a swing feel, start by stressing the off-beats in everything you sing. When singing in 4/4 time (ie 4 beats in a bar) in classical music the stress tends to be on beats 1 and 3 whereas in jazz the stress tends to be on beats 2 and 4. Try saying "1, 2, 3, 4" while clicking your fingers on beats 1 and 3, and then on beats 2 and 4. Beats 2 and 4 are known as off-beats, and by stressing them we get closer to the essence of swing. Now try singing any familiar standard, such as All of Me by Gerald Marks and Seymour Simons. To help the song swing, click your fingers on the offbeats (2 and 4) as you sing. Now try stressing the off-beats with your voice.
For example: "All of me, why not take all of me. Can't you see, I'm no good without you ..."