Harmonicity

Mimic the acoustics of sound sources in perfect unison

“Oh my god Art Garfunkel’s voice and those harmonies. My goosebumps have goosebumps.”

A Harmonicity pattern is when multiple notes are in precise harmonic alignment, i.e. all the sound frequencies produced are perfect integer multiples of a single fundamental frequency (i.e. part of one harmonic series). You know harmonicity when you hear it. These moments have consistent, distinctive features: exact tuning, rich and pronounced overtone resonances, contrapuntal motion in and out of alignment, and heavy reliance on perfect intervals like fifths, octaves, and unison. The more abrupt the onset of perfect harmonic alignment, and the longer that alignment lasts, the more likely audiences are to experience chills.

There are two theories of why a Harmonicity pattern can induce frisson: 1) perfect harmonic alignment can create unsettling ambiguity that triggers a frisson-inducing fear response, and 2) frisson in response to harmonicity evolved as a reward to encourage pro-social behavior.

 

One view is that harmonicity confuses our auditory system for separating sounds from different sources, creating unsettling ambiguity. Harmonically-related frequency components generally come from the same sound source; each of our voices has a slightly different fundamental frequency and overtone resonance distribution. Our ear uses these components to, for example, distinguish the voice of a man vs. a woman or the voices of two different women. When we hear perfect harmonic alignment, however, our brain can struggle to differentiate the parts from the whole. If two musicians are perfectly aligned, our brain may be temporarily tricked into thinking there is only one instrument playing. Or if one singer manipulates formants to bring out harmonics, it can similarly confuse our brains and make it seem like there is more than one sound source. This ambiguity, it is thought, can momentarily scare us and give us chills. 

 

A different view is that harmonicity produces frisson as an evolutionary reward for pro-social behavior. This perspective emphasizes that one of the primary reasons that music evolved among humans was to help us form social bonds. Given that a harmonicity moment requires musicians to listen carefully and adjust to one another, its plausible to think our brains began to reward this empathetic behavior with pleasurable chills. This view is supported by neuroscientist Matt Sachs’ breakthrough research that found people who get chills from music have more fibers in the part of their brain responsible for social-emotional communication. We also see anecdotal evidence for this view in conversations with choral and a cappella singers. Many singers report unforgettable moments of harmonic unison during rehearsals that helped foster a lasting kinship across their performing group.

Our data indicates that when multiple vocalists perfectly align during sustained notes or chords, this can often induce frisson in listeners. The key to this method is that the significant note length allows vocalists to adjust to each other in order to find and maintain harmonic alignment. It usually takes a second or two after the onset of a sustained chord for vocalists to hit each of their notes just right. Long notes or chords also enable singers to bring out overtones and achieve richer sounds. Given how sensitive our ears are to the human voice, sustained perfect vocal harmonic alignment is highly effective for frisson.

Note: This method is almost always paired with the Resolution pattern.

In chills-inducing passages, some of the most reliable techniques we see composers and performers using to achieve this method include:

  • Sudden shift from solo to ensemble vocals on the sustained note, typically after a passage featuring only the lead vocalist
  • Sudden alignment between a lead and backing vocalist (or two sections of a choir) after a passage where the two singers were moving in unison but not perfectly aligned
  • A capella arrangements featuring the same vocalist singing every part, after pre-recording each part separately (e.g., Sam Robson and Peter Hollens)

Don’t interpret this to mean that any sustained consonant interval sung by vocalists will automatically give listeners chills. Our data suggests that when using this technique, it helps to:

  • Feature these long notes when listeners are already focused on the harmonic progression (e.g., end of a cadence, climax of a phrase) to make them as conspicuous as possible
  • Precede these holds with passages that feature shorter rhythms and increasing dissonance (harmonic misalignment) to accentuate the contrast of the harmonicity moment
  • Maintain alignment throughout the long note, rather than wobbling in and out of alignment repeatedly, to create space for a positive listener appraisal response

Anecdote: Choral music specializes in creating powerful ensemble harmonicity moments; this is likely a key reason why why choral music was such a popular submissions to our dataset of frisson moment

Our data indicates that when you feature multiple lines moving in and out of harmonic alignment several times in quick succession, this can often induce frisson in listeners. The key to this method is contrapuntal motion that makes the harmonic movement smooth. When done right, these passages can create a satisfying sensation of prolonged, cohesive harmonicity. Oblique motion in particular, where one voice is stationary and the other voice moves, encapsulates this approach of one sound source moving in and out of alignment with another. This method requires talented musicians to pull off, making it rare and highly effective for frisson.

In chills-inducing passages, some of the most reliable techniques we see composers and performers using to achieve this method include:

  • Oblique motion, especially harmonic drones against melodic lead lines (e.g. vocal traditions like Aramaic chant and instruments like bagpipes)
  • Parallel motion across a melodic line, often in vocal or instrumental duets, where the melody pauses on more consonant intervals to create harmonicity moments
  • Polyphonic motion between vocalists or overtone-rich instruments like steel-pedal guitar, crotales, or bowed metal instruments like vibraphones

Don’t interpret this to mean that every time you feature a drone in your music, listeners will automatically give listeners chills. Our data suggests that when using this technique, it helps to:

  • Drop out the surrounding texture, or switch to a monophonic texture, to make these harmonic motions in the lead line as conspicuous as possible for listeners
  • Place these motions at the end of a section or high point of a phrase when listeners are already focused on the harmonic motion
  • Leave rests after harmonic alignments, or reduce the texture to only the drone or bass line, to create space for a positive listener appraisal response

Our data indicates that when you feature polyphonic singing with vocal techniques that bring out overtones in unusual and pronounced ways, this can often induce frisson in listeners. Global polyphonic folk traditions are extremely popular and consistent in our dataset of listener frisson moments. While they are diverse, these traditions all bring out overtones in atypical ways to create alluring harmonicity moments. Given how rare and difficult they are, these singing techniques are highly effective for frisson.

In chills-inducing passages, some of the most reliable techniques we see composers and performers using to achieve this method include:

  • Larynx and vocal folds manipulations to create a “throat-y” sound that brings out lower overtones (e.g. Sardinian cantu e tenore or Kargyraa throat singing)
  • Throat and vocal muscle manipulations to create a “nasal-y” sound that brings out upper overtones (e.g. Bulgarian folk music or American bluegrass)
  • Microtonal techniques and other subtle pitch adjustments away from equal temperament

Don’t interpret this to mean that any polyphonic singing will automatically give listeners chills. Our data suggests that when using this technique, it helps to:

  • Emulate the harmonic series by featuring closer harmonic intervals in higher registers and wider harmonic spacing in lower registers
  • Surround these harmonies with sparse, percussive backing instrumentals so the drawn-out vocals occupy the majority of the frequency range and are as conspicuous as possible
  • Sustain and repeat these harmonies to re-assure listeners the unusual resonances are intentional and create space for a positive listener appraisal response

Our data indicates that when a vocalist or instrument holds a note, then brings out a harmonic overtone or undertone to such an extent that the harmonic is heard as a second simultaneous note, this can often induce frisson in listeners. This method is effective because it is often easier for a musician to achieve perfect harmonic alignment with themselves than with another performer. Even identical instruments sounding the same note (e.g. two violins or two vocalists) tend to produce slightly different overtone resonances. Its technically difficult and rare, however, for musicians to be able to produce and accentuate perfectly aligned harmonics, making this method highly effective for frisson.

In chills-inducing passages, some of the most reliable techniques we see composers and performers using to achieve this method include:

  • Overtone singing where singers manipulate their vocal folds to accentuate harmonics
  • Artificial harmonics on string instruments (esp. violins and electric guitar)

Don’t interpret this to mean that anytime you feature harmonics that listeners will automatically get chills. Our data suggests that when using this technique, it helps to:

  • Pair self-harmonization with slow tempos, long note lengths, and minimal rhythmic complexity to make the harmonics especially conspicuous
  • Feature self-harmonization during solo sections with minimal or no accompaniment to focus listeners on the sound of the harmonicity and prevent non-acoustic distractions
  • Sustain and repeat self-harmonized notes throughout a melodic line to re-assure listeners and create space for a positive listener appraisal response

Our data indicates that when you feature an instrument or vocalist repeatedly alternating certain consonant intervals, especially perfect fifths and octaves, this can often induce frisson in listeners. We think this method is effective because it creates fleeting moments of perfect harmonic alignment between the decay of the previous note and the entrance of the next note (assuming the tuning is precise). This likely explains why artists either rapidly repeat these intervals and/or sound them with heavy reverb when using this method. Given how rare repeated fifths and octaves are in Western melodies, this method is highly effective for frisson.

In chills-inducing passages, some of the most reliable techniques we see composers and performers using to achieve this method include:

  • Rapid alternating fifths or octaves
  • Rapid repeating arpeggios featuring movement by fifths and octaves
  • Slow-decay timbres like piano with pedal down, guitar with added reverb, etc.

Don’t interpret this to mean that every time you alternate back and forth by fifths listeners will automatically get chills. Our data suggests that when using this technique, it helps to:

  • Feature this method during song intros before a melodic and harmonic context has been established to focus listeners on the acoustics and harmonicity
  • Surround these repeating intervals with reduced textures and sparse arrangements (often unaccompanied solo sections) to make them as conspicuous as possible
  • Repeat and sustain these intervals to create space for a positive listener appraisal response

Listen to thousands more example clips in our Frisson Database