If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content
Current time:0:00Total duration:4:37

Lesson 6: Constant versus changing time, adding triplets, and duplets

Video transcript

- [Voiceover] At times, especially in popular dance forms the meter will remain constant. All ballroom dancing fits into this category. A march would also fit into this category, remaining constant, usually in two-four. It is also the case with most music from the 18th and 19th centuries. In the latter part of the 1800's and into the 1900's, composers started to feel free to change meters during a movement or work, sometimes quite often. The actual meters remain as we have discussed. If we look at the last movement of the Sam Jones "Cello Concerto", we can see some simple changes of meter, from two-four to three-four, back to two-four, then three-four and four-four. ("Cello Concerto" by Sam Jones) Another simple example is in Phillip Glass' "Harmonium Mountain". At this excerpt, he mixes the meters two-four, three-four, and four-four. ("Harmonium Mountain" by Phillip Glass) If we look at David Stock's work called "Blast" written in 2010, we find a more complicated section of meter changers, using five-eight, seven-eight, three-four, and four-four. ("Blast" by David Stock) If we look at a four-four measure, we have learned that the measure can easily be divided by using various note lengths. Half notes, quarter notes, sixteenth notes, thirty-second notes and so forth. But what if a composer would like to divide one of those quarter notes into three equal parts to create more rhythmic interest? We accomplish this by adding a three above or below a group of three eighth notes. The three signifies that three notes are performed during the time of one quarter note. Let's again look at Phillip Glass' "Harmonium Mountain". In this passage we see the violins playing the groups of three called triplets, and the violas and cellos are playing quarter notes. Then the violas join the violins playing triplets, the cellos play the eighth notes and the double basses play the quarter notes. ("Harmonium Mountain" by Phillip Glass) This method of changing duple notes to triple notes can work in any duple meter. The composer can also divide the triple beat in different ways. For example, instead of three eighth notes in a beat, we could see an eighth note and a quarter note, or a quarter note and an eighth note. We still need the number three above or below the notes. If we look at Ravel's "Daphnis et Chloe" the meter is five-four, but Ravel adds the three for each part to create triplets. You will see that he doesn't continue to write the three during the continuation of the excerpt, assuming that the performer understands the pattern. ("Daphnis et Chloe" by Ravel) The triplet is the most common variation within a meter, but there could also be, for example, five notes within a quarter, again with a five above or below, or six, or quite frankly any number that is not common to the meter. In a triple meter like six-eight, one could do the same. Six-eight can be one dotted half note or two dotted quarter notes, or six eighths, or twelve sixteenths. We could also have a rhythm of quarter, eighth, or eighth, quarter. Or any combination that adds up to six eighth notes. If a composer wanted four notes during a dotted quarter note, the number four would go above or below the group of notes. As you can see, the notation of rhythm can become very complicated. We will discuss this in later lessons.