Voice Parts
If you listen to a group of musicians playing together, you will notice that there are times when one person plays a sustained note or chord while another plays a moving part. Because the Piano is capable of playing many notes at the same time, this same musical technique can be used by one player. When you have one note sustained with a moving part over or under it, the lines are written as individual voice parts, with the note stems going in different directions. This originally comes from choral music, where a chord is made up of three or more notes sung by human voices. The following example is a simple demonstration of voice parts, containing a moving voice in the middle part.
When playing music containing individual voice parts, it is often necessary to sustain a note by keeping a key pressed down while playing other notes with other fingers on the same hand. This can be difficult at first, and requires a great deal of slow, concentrated practice before it becomes automatic. Here is an exercise to help you develop this technique.
One of the simplest uses of voice parts is a sustained bass note at the beginning of each bar, with an inner rhythmic part played by other fingers of the left hand on the remaining beats of the bar. In this example, the technique is used to provide a waltz accompaniment.
Here is a study by Czerny which uses the same technique in * time. All the bass notes are played by the 5th finger of the left hand. Be sure to hold each one till the end of the bar, so that it keeps sustaining under the chords played by the other fingers of the left hand. Notice that both hands are reading treble clef in this piece.
