I recently posted a music theory puzzle of a Bach chorale excerpt which contains parallel fifths. I was reminded that some music students may not understand why parallel fifths are considered “bad.” In fact, a great deal of contemporary music uses parallel fifths and to our modern ears they don’t usually sound wrong.
The usual answer is that it “destroys the independence” of each voice, which is true. However, there are also some practical reasons for avoiding parallel fifths in compositions for a cappella voices – it’s hard to sing. ComposerOnline put together an nice video presentation that demonstrates this.
There are also some historical reasons why Baroque Era composers began consciously avoiding parallel fifths. Beginning around the 8th or 9th century polyphony (the idea of using multiple melodic lines together, rather than just unison voices or voices with drones) developed. The religious chants were sung in monasteries by both men and boys in octaves already, so it seems obvious in retrospect that they might also sing them in parallel fifths. This is known as “parallel organum.” David W. Barber describes organum in his book, “Bach, Beethoven, and the Boys: Music History As It Ought To Be Taught.”
Gregorian chants developed into something called organum, which was all the rage of the ninth to 12th centuries. In its simples form, this consisted of singing the same Gregorian tune as the monk beside you at the interval of a perfect fourth or fifth.* This is harder to do than it sounds, and requires the kind of concentration that monks are especially good at.
* Barber’s footnote reads, “It’s not worth explaining why fourths and fifths are called perfect. Just take my word for it.”
Parallel organum later evolved into “free organum,” although it still frequently used parallel fourths or fifths between the two voices. It’s quite a distinctive sound. Here’s an example.
By 1600 ( early Baroque Era) the sound of parallel motion had started to sound old fashioned. Even in instrumental music, which doesn’t have the technical difficulties writing for voices have with parallel motion, composers avoided the use of parallel fifths and octaves. When they were used, they were sometimes used to symbolize something rustic or old fashioned, such as in Beethoven’s 6th (“Pastoral Symphony”).
It’s not until the 20th century when composers began to start using parallel motion with more frequency. It’s now a sound that is ubiquitous in many styles of music. I find it interesting that a musical sound can go from 5 centuries of extensive use to 3 centuries of avoidance, to being used frequently again. Not to mention musical styles other than “western European art music” that use parallel motion all the time. Regardless of your stylistic interests, both the use and avoidance of parallel fifths is something that is worth learning about. The distinctive sound of parallel fifths still has an ability to elicit a powerful reaction on us.