Why Does Jazz Sound So Random?

Improvisation and controlled randomness are essential features that define the jazz genre, and have formed part of its characteristic charm and personality ever since the format was first conceived by African American slaves in Louisiana in the early 1900’s. These slaves – the true pioneers of jazz – would sing and play free-form songs about freedom and hope as they worked the fields. It’s fair to say there is no other form of music as ‘random’ as jazz.

But the music theory behind why jazz sounds so much more unpredictable than other forms of music – like pop, hip hop or blues – is actually quite complex. Luckily, we’re here to simplify it, so whether you’re a clueless jazz newbie, or seasoned jazzy maestro, sit back as we demystify the randomness of jazz!

Happy Accidents

Some of jazz’s best moments are borne of capricious musical discoveries during passages of adventurous improvisation. Whereas much of today’s music uses simple chord progressions with common major and minor chords, jazz tends to use complex chord progressions, made up of unusual chords. Key changes are frequent in jazz, and its rhythms tend to be loosely syncopated rather than rigid.

The mysteries behind the randomness of jazz are in fact as beautiful and intriguing as the music itself. While jazz may seem random in comparison to other forms of music, a skilful jazz musician has the vocabulary to articulate the method in this madness, much as a mathematician can make sense of a complex equation that looks like a random collection of symbols and numbers to the rest of us.

Complexity Can Sound Random

Jazz is measurably more complex than many other music genres – in terms of music theory metrics like the number of chords used, the complexity of those chords, and the numbers of key changes per song. However, this is a broad generalisation. As we know there are very few absolute rules in music. Some other genres like classical, and metal also make frequent use of musical complexity, and yet they sound nowhere near as random as jazz.

And of course, simplicity and restraint are just as valuable as complexity in the art of musical composition. Minimalism is also a powerful tool to express human emotion, and a lot of jazz is quite minimal. In fact, one of the most common key scales used for jazz songs (the pentatonic minor) contains only 5 of the 12 possible notes!

So musical complexity is not the only feature that imbues jazz with its characteristic air of freedom and randomness. Often what sets jazz apart is the emphasis on improvisation and spontaneity.

Improvisation and Spontaneity.

Unlike many other forms like classical, in which musicians play predetermined well-prepared passages, jazz emphasises spontaneous delivery of unique melodic solos and passages. The songs are literally different every time.

There are levels to improvisation in jazz, and no boundaries as to what parts of a song can be improvised. In some jazz songs each player has a chance to solo over a predetermined theme or motif. In others the chord progression and drum rhythm might be set in stone, repetitive and predictable, with perhaps only the lead horn player trilling out the odd improvisational solo.

There are forms of jazz that completely eschew any adherence to harmonic and rhythmic structure or convention, in which absolutely everything is improvised. Jazz musicians feel that having the freedom to play whatever they choose gives them far greater expressive and emotive range than being bound to sheet music, which limits the possibility for unique articulations and expressions of a musical feeling or theme.

Whereas in other genres a player may noodle about until she stumbles on a good riff, and then loop that riff over 16 bars, a jazz player is more likely to be soloing contemporaneously, painting unique passages that change and evolve over each bar. This, aficionados say, keeps the music exciting, as the listener never knows what to expect.

Recent studies have suggested that expectation – and the defiance thereof – may lie at the very heart of the mystery of why humans seem to enjoy the patterned arrangements of sound waves that we know as music.

Can You Just Play Any Note in Jazz? (Why Jazz is Literally Not Random)

The answer, of course, is no. But yes.

As we’ve seen, spontaneity and improvisational soloing are key features of the jazz genre, but there is a lot of skill – both theory and practice – that goes into being an effective improvisational jazz player. The ‘randomness’ which which a great jazz player can express himself musically is in fact bounded within a rigorous understanding of some very sophisticated musical theory.

Produced for broad market appeal, today’s pop music – although infused with diverse influences including blues, Afro-Caribbean, jazz and classical – tends to be quite musically simple. Most pop songs use one of a handful of key scales or modes (major and harmonic minor are both ubiquitous), and generally stick to simple progressions of only 2,3 or 4 chords. The chords in pop tend to be only minor and major chords, with perhaps the odd 7th thrown in for flourish.

Jazz on the other hand offers far more tonal intricacy, often utilising complex chord progressions with more complex structures, and many different unusual chords, with alternative voicings for each.

Classical music conventions dictate that when soloing over a chord, you should stick to the complimentary notes of the same scale, but avoid the notes that clash with the notes of the chord itself. At times the soloist might use voice leading to build tension, anticipate key changes, or accentuate resolutions.

The soloing that a jazz player weaves over chords will often make use of these same musical conventions.

However, the greater chordal complexity of jazz means that, even when they are adhering these sorts of norms, jazz players will tend to have a lot more freedom in terms of the notes available for them to play at any particular time. The chord player might also have much more freedom as to which chords they play, and which voicings and inversions they use.

And of course, jazz does have structures and conventions of its own. Think of the ubiquitous 4 5 1 chord progression. Jazz standards – common melodies that most jazz musicians practice their soloing over – are like lexicons for musicians to study the complex language of jazz. Most jazz songs do in fact have an overarching motif , musical idea or chord progression. But the magic of jazz happens as each musician improvises over it to accompany that core idea, adding unique touches and melodic flourish each time.

Instead of saying – “Your solo was in the wrong key,” rather say,” “That was very jazzy!”

But is your jazzy friend playing the wrong key? what is ‘wrong’ when there are no rules? The truth is your jazzy friend might simply have found an unexpected complimentary key. Perhaps she was playing in a 9-note Spanish scale, that just happened to coincide with whatever scale you thought you were playing! The only truth in music is, if it sounds good, it is good! You need to trust your ear as a musician, and be your own judge at the end of the day.

How Can I be More Jazzy and Random?

Jazz is a beauteous collision of musical chaos and ordered sophistication. But instead of just channelling raw chaos (although that might be helpful too), some rigorous textbook training may actually be what you need to do in order to sling some capricious randomness at your friend’s next jam session. You might want to:

• Learn some new chords,
• grind over those neglected, uncommon scales, and
• practice banging out some challengingly complex syncopations and polyrhythms.

It takes time and effort so don’t be discouraged if jazzy greatness doesn’t happen for you over night. Improvisation sounds effortless by nature, but it’s usually the result of much unseen honing of the musical crafts.

Randomness is a Skill

‘You have to learn the rules before you can break them.’ The adage is as old as music itself. A good jazz player hears what chord is playing and can identify it by ear from a huge repertoire of chords. Since he has the skill to pull it off, he can choose whether to colour inside or outside of the lines, or even ignore them completely, for the sake of emotional impact. He may be able to defy convention by going totally out of the expected key scale, but then find another unexpected, yet brilliant resolution through his knowledge of other modes scales, and devices. In essence he uses randomness as a musical force to better expresses the feelings and musical themes he is trying to convey.

Haters Gon’ Hate But Y’all Know Jazz is Great!

Jazz is in fact a highly sophisticated, complex musical form, which is why players accustomed to styles like blues, rock or reggae, may struggle at first to pivot their skills when starting to learn jazz. But, as we’ve seen, sophistication is not inherently better than simplicity in the world of music. Randomness is certainly not inherently better than orderliness, and as we’ve seen jazz is a paradox: simultaneously random and orderly. Jazz is simply a different set of musical sensibilities, one with a vastly different set of vales to classical music, for example. Whether it’s any good is really a matter of personal preference and taste. Views around jazz tend to be radically polarised.

‘Jazz for Study’ Much?

Interestingly, because of its randomness – and its constant playful defiance of musical expectation – jazz music may have even greater neurological benefits than other genres.

As Jazz Stalwart Bill Evans Put it: “There are no wrong notes, only wrong resolutions.”

Jazz’s legendary spontaneity make it endlessly flexible and adaptable. As long as each player is fluent in the basic vocabulary of jazz, any players can play together on the spur of the moment anywhere in the world and jam coherently.

So, while jazz can seem random, the best jazz is a result of capricious improvisations and happy accidents on the part of accomplished musicians who are fluidly navigating some highly advanced musical concepts.

TRUE Randomness in Music?

A good example of true musical randomness (and why jazz is not actually truly random) is the birth of procedural music. When computer scientists and early audio engineers programmed computers to output TRULY random music, unguided by any mathematical form or function except randomness, the results were excruciatingly bad music, utterly un-listenable in comparison to the gorgeous intricate passages, funky improvised lines, or soaring crescendos of actual jazz music made by humans of any period.

That said, in recent times, txt2audio AI music generation engines like Suno and Udio have emerged, offering remarkably ‘lifelike’ and fun results – including convincing lyrics! These tools are evolving with fine-grained control as a key priority development avenue, bridging the gap between AI music and traditional digital audio workstations, like FL Studio, over time. Though, like other AI art tools, they’ve faced their share of push-back, these new fangled systems are akin to the new musical instruments, just as Large Language models are the new pen, and AI art software can be thought of the the new paintbrush. The limits of what’s possible with algorithmic composition have been shattered. These generative music manufacturers / conjurers (depending on your viewpoint) are here to stay, and they’re already changing the way musicians work and create.

However examples of actual randomness have crept into contemporary music.

The highly acclaimed, gorgeously jazzy soundtrack to the video game Zelda – Beath of the Wild for example, makes use of a kind of staggered musical arrangement algorithm that sees certain interwoven piano passages begin at slightly randomised times in relation to each other. This makes the song seem slightly different and new every time the protagonist sets forth into melancholic wild-lands. This, and other subtle random touches in how the game’s musical elements are triggered, give the soundtrack a somewhat jazz-like improvisational quality. Small wonder the score is praised as one of gaming’s best.

Clever programmers have even envisaged (and possibly begun work on) digital audio formats in which musical elements could be randomised within predefined parameters. This would allow even digitally streamed music to be different and unique every time you play a song!

The AI Music Revolution

As mentioned earlier, the landscape of musical creation has been fundamentally transformed by recent advancements in generative AI. Platforms like Suno and Udio, along with speech and voice cloning engines now offer unprecedented capabilities, allowing users with no formal musical training to create complete compositions in seconds simply by describing what they want.

Udio, developed by former Google DeepMind researchers and launched in April 2024, represents a particularly significant advancement in this space. Backed by prominent artists including will.i.am and Common, along with distribution platform UnitedMasters and venture capital firm Andreessen Horowitz (a16z), Udio can generate a mastered track in under 40 seconds based on simple text prompts.

These tools raise fascinating questions about the nature of musical creativity and improvisational spontaneity. While jazz has traditionally been valued for its human spontaneity and the subtle expressiveness that comes from years of practice, AI music generators create an interesting parallel – producing unique compositions each time, but through algorithmic processes rather than human intuition.

This convergence of jazz’s improvisational ethos with AI’s generative capabilities presents both challenges and opportunities for musicians. As will.i.am noted regarding Udio, ‘This is a brand new Renaissance and Udio is the tool for this era’s creativity; with Udio you are able to pull songs into existence via AI and your imagination.’

The question remains: can AI truly capture the essence of jazz’s controlled randomness, or is there something inherently human about jazz improvisation that algorithms can approximate but never fully replicate? Perhaps the most interesting development will be how human jazz musicians incorporate these new tools into their creative processes, potentially creating hybrid forms that combine human expressiveness with AI-generated foundations.