To become a good Jazz singer it is essential to have control over exactly where in the bar you sing each note and also where you remain silent. A good way to develop this ability is to concentrate totally on rhythm by using only one note, and singing it in all different rhythmic positions within a bar.
The following example begin with a pair of eighth notes on different beats within a bar, and then moves on to groups of four notes sung in various positions. The aim is to be able to instantly repeat a rhythm both by ear and from written music. On the recording, each bar is followed by a space for you to sing the rhythms in time with the band.