On the piano, a trill occurs when you flutter your fingers very quickly between two notes that are close together, either a half-step or whole-step apart. So, what do you call fluttering between two notes that are farther apart? Well, you call it whatever you want, but the world of music calls it a tremolo.
To play a tremolo, pick an interval — anything larger than a whole-step — and alternate playing the two notes as quickly as possible. Like a trill, a tremolo sounds as if you’re playing a bunch of 32nd or 64th notes. But unlike the notation for a trill, which just puts tr above one note, the notation for a tremolo actually shows you both notes that your fingers rumble between.
You see that the two notes of a tremolo have the same note length. At first glance, it looks like there are too many beats in each measure of this notation, but the three diagonal lines between the notes signal that this is a tremolo and therefore the two notes share the note length. You only count the beats of the first note.
You can also play tremolo chords. All you do is break the chord into two parts: a bottom note and the remaining top notes. Shake the chord into a tremolo by alternating between the two parts as quickly as possible. Tremolo chords may look intimidating, but if you can play the chord, you can play the tremolo.
Here’s a chance to play a few tremolo chords. For the first measure, put your hand in position for a G major chord and rock between the top notes (B and D) and the bottom note (G) very quickly. Move to the next measure and do the same with a second inversion C chord, and so on.
Check here to solidify your understanding of the tremolo.
Tremolo chords come in handy when playing rock ’n’ roll, especially as part of a band. A tremolo turns the otherwise dull task of playing straight chords into a sizzling rhythmic romp.