When we improvise on piano, we generally play some sort of melody with our right hand while the left hand provides an accompaniment. Or sometimes the accompaniment is also in the right hand under the melody in the form of chords or arpeggios.
But have you ever tried playing 2 melodies at once with your right hand? The concept is like in a chorus. The melody is (usually) sung by the sopranos, and the altos and other voices sing melodic lines under the melody.
We can do this on piano too, even when we're improvising. I've written a short example above, on an Eb Blues (but you can use this technique in any type of music, even pop). Don't get too hung up on getting the "alto" part to be perfect. The idea is to simply play a "melody under the melody," even if the 2nd line is repetitive or extremely simple. (Play the alto voice in my example: it's doesn't sound so great on its own. But when played with the melody, it adds richness and interest.)
You can use this technique to great advantage on jazz tunes such as "Autumn Leaves," pop/rock ballads like Billy Joel's "Piano Man," church hymns and songs, and bossa novas. You can even improvise an alto part while you're taking a solo!
Have fun practicing and experimenting with alto parts on your favorite songs. They can add a new layer of texture to your piano playing and take your music "to the next level."
Here's a little "2-voice improv" on John Coltrane's tune, "Bessie's Blues." Good luck!
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