A hemiola is a rhythmic device that involves superimposing 2 notes in the time of 3 – there are 2 types you will come across – horizontal hemiola and vertical hemiola.
A horizontal hemiola occurs in a piece written in triple time where the music is suddenly changed to “feel” like it has altered from triple time (counting in 3’s) to duple time (counting in 2’s) without any alteration of the time signature.
Here is a short phrase written in triple time:
You can see and hear how the beats are counted in three’s.
However, if we add ties to the crotchets (quarter notes) you can see/hear how we have temporarily “imposed” the feel of 2 beat time on the piece. The time signature of the piece is still 3/4 (3 quarter note beats in a bar), but the piece feels like it has 2 beats in a bar.
In other words, a hemiola is where a feel of 2 beat time is temporarily imposed upon a piece which is actually written with 3 beats in a bar.
Composers have typically used the hemiola to add rhythmic interest to a piece of music – it feels like the music is getting quicker/intensifying. They were historically very popular as a musical tool used at cadences up until the end of the Baroque period.
Here is an example from Handel’s “And The Glory of the Lord” taken from his Messiah:
You can see and hear how the music in bars 9 and 10 suddenly feels like it is structured into groups of 2 beats rather than the 3 beat grouping of the time signature.
Here is another example taken from the Classical period by Mozart in one of his piano sonatas:
You can hear how the hemiola intensifies the drama of this section of the sonata.
Horizontal hemiolas have remained popular with some contemporary composers.
One of the most famous examples is the rhythm from “America” by Leonard Bernstein from West Side Story:
Bernstein’s use of the 3:2 rhythmic pattern adds wonderful intensity and excitement to the music.
A vertical hemiola is when multiple parts are playing rhythms of twos and rhythms of threes simultaneously:
This creates a wonderful cross rhythm effect. Vertical hemiolas are another fantastic way to add rhythmic energy and excitement to a piece of music. The 3:2 rhythmic relationship is a fundamental rhythmic building block of polyrhythmic music from sub-Saharan Africa.
It has also been used by Western composers over time. Here is an example from the final movement of Beethoven’s Piano Sonata in F minor. You can hear the intense drama it helps create as the triplets of the right hand play contrast with the duplets of the left hand:
I hope that you have found this lesson helpful. Please do get in touch through social media if you have any questions.