Musicologists Find the Reason Composers Can't Resist Instrumental Solos

Given a multitude of instruments, why would they choose just one?

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From the elaborate piano breakdown in Eric Clapton’s “Layla” to the guitar solo in the Beatles’ “While My Guitar Gently Weeps,” the instrumental solo is an iconic part of pop. But to a musicologist, it doesn’t quite make sense: Given an orchestra full of instruments to use, why would a composer only use just one? Niels Chr. Hansen Ph.D. of The Ohio State University investigated this musical conundrum in a recent Music Perception paper, concluding that instrumental solos might be an especially effective tool for a particular kind of emotional manipulation.

In the study, published in early July, Hansen, a postdoctoral researcher at Ohio State’s Cognitive and Systematic Musicology Laboratory, studied 330 orchestral excerpts to see whether there’s a link between instrumental solos and one particular emotion — sadness. “The idea came up because a lot of previous studies have looked at linking musical parameters like melody, rhythm, and harmony to the acoustic features associated with sadness,” Hansen says. What he and co-author David Huron, Ph.D. wanted to know was how and whether instrumentation — specifically, solo instrumentation — was used to do the same. There is, after all, something especially sad and lonely about the sound of a solo instrument.

“In a way, it seems like a bit of a paradox that a composer would ever decide to feature just a single instrument when he or she has a whole symphony orchestra of 80-100 highly skilled professional musicians just sitting there!” says Hansen.

So, Hansen and Huron, a professor of music, set to work characterizing 330 random excerpts from orchestral songs that did or did not contain an instrumental solo. Those same songs were also appraised for sadness using seven sadness-related factors, which included the use of a minor key, tempo, soft or loud dynamics, and instrumental articulation, among others. Comparing the two data sets showed that 74 percent of excerpts classified as “sad” or “relaxed” contained solos — that’s twice as the number of solos in non-sad excerpts (only 37 percent).

To further define the relationship, the team looked at whether those seven sadness-related characteristics could be used to predict whether a song would have a solo or not. Sure enough, they generally did — smooth, joined-together notes (legato articulation) and quiet dynamics were most tightly linked — underscoring the existence of a link between the use of instrumental solos and musical sadness. And this relationship doesn’t just apply to orchestral music.

To anyone who’s listened to the haunting guitar riff in Led Zeppelin’s “Stairway to Heaven” or the brain-melting solo at the end of “Hotel California,” the inherent connection between sadness and a solo instrument is a no-brainer. But describing that relationship in concrete terms isn’t quite as easy. Hansen’s theory is that the reason solo instruments are so good at conveying sadness in all kinds of music is because the sound of a single intstrument mirrors the isolation we impose on ourselves when we are sad.

“If you think of the times that we feel sad as human beings, it is most often when we are alone,” he says, noting evolutionary psychology research showing that isolation is necessary for self-reflection. “[The] sound of a single instrument might remind us of situations in our own lives where we have been lonely or sad (and therefore may have isolated ourselves).”

Supporting this idea, previous research on the musical qualities that convey sadness has also suggested that they mimic the way humans speak when they’re sad: quietly and slowly, in a low pitch range that allows for little else than mumbled and monotone articulation. “A single instrument will also require less energy overall and produce quieter sounds that are more similar to the features of sad speech and sad music,” says Hansen. Even the wailing of a bending guitar string (he recommends you check out Gary Moore’s “Still Got the Blues”) can mimic the sound of a human crying.

The melancholic sadness that instrumental solos symbolize isn’t the same thing as grief, he points out. “This low-arousal state is very different from the high-arousal state of grief where you will be loudly crying to attract the attention of others around you who might be able to help you. That is very different from sadness.” The distinction is what you might hear in the difference between Adele’s unabashed gut-wrencher “Someone Like You” and the more subdued sadness of Frank Ocean’s “Bad Religion.”

Of course, in the vast canon of music you’re bound to find instrumental solos meant to convey emotions other than sadness, or even those deployed for purely structural reasons. The ecstatic sax solo in Carly Rae Jepsen’s “Run Away With Me” is all the proof you need. Though solos are particularly useful for awakening our love of sad music, they’re also good for musicians to simply show off.

“Just like in classical music, solos can also be used to show the virtuosity of a given performer, as formal transitions bridging the way to new sections, or simply to break the monotony of constantly changing between the verse and the chorus,” says Hansen.

“If you think about it, the hooks of many popular songs are actually parts of instrumental solos that are repeated again and again. Such passages are rarely sad.”