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What I Learned Writing an Album in Just Intonation

159 points| pierrec | 1 year ago |osar.fr | reply

93 comments

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[+] pierrec|1 year ago|reply
I'd love to get some feedback on this, because I'm not sure I've hit the original goal of this article.

For a long time, the topics of just intonation, harmonic lattices, and of their relationship with temperaments were difficult for me to understand, despite reading the theory on them. It's not until I applied the concepts that could say I understood them.

I tried writing the "missing article" that would have given me this understanding right away, banking on the added value of interactive figures. Right now I suspect that I failed in the same way as my early readings did: this article might be hard to understand unless you're already familiar with the topic, which is a bit of a chicken-and-egg problem. I think I glossed over some concepts, and it sometimes looks like I'm pulling numbers out of thin air in some examples. Nonetheless I hope it will help some people understand these topics. Maybe what's needed is a slower-paced version of this as a longer series.

[+] thrtythreeforty|1 year ago|reply
The interactive harmonic lattice, with the commas clickable and audible, is first rate and is the best interactive illustration of JI problems I have yet seen.

It is not quite clear from the explanation, that since the "3" direction is also dividing by 2 implicitly, the note confusingly labeled "3" is really just 3/2 - the perfect fifth. Similarly, the note labeled "5" is actually what we hear as the 12TET major third - clarifying a couple of examples on this lattice (or playing a chord) would be good.

Then, the thing I think that might help is driving the point home a little more by creating a comma by hand - a "knight's move" to another tile 5 horizontal and 3 vertical, creates a ratio that almost but not quite undoes itself. The (unwieldy) math is 1*3*3*3*3*5*5/2/2/2/2/2/2/2/2/2/2/2 = 0.9887, and this is what creates the commas in JI. Hiding the octave transpositions, while making for a neat visualization of the lattice, confuses the underlying issue.

[+] klik99|1 year ago|reply
I think you need some info in the start of the article about why 12tet was invented, what problems it was solving and how it fails. Like - In Bachs day you'd have to retune the instrument if you changed key signatures and you could only modulate a few steps away before the ratios sounded really bad. So 12TET opens up the possibilities to modulate far away from your original and requires less retuning, at the cost of adding various amounts of dissonance to intervals. I always find it interesting that each key signature in 12TET has a unique sound (Like CMaj vs EMaj) due to inconsistent ratios in perfect fifths, etc, and that "offness" is not necessarily a bad thing. You could also mention what most people think "microtonal" is (adding extra notes in between half steps) and why just intonation is different.

IMO music is all about the balance of the harmonic/expected and dissonant/unexpected at various timescales. The experience of Just Intonation is interesting because at first it sounds wrong due to us expecting 12TET but once you recalibrate your expectations it sounds more pure and harmonic, like how choirs or string quartets slip into simpler ratios instead of sticking exactly to 12TET.

I think with some more context/succinct summary at the beginning (which is REALLY HARD to write about for a general audience) the rest of the article would be more clear for people not steeped in music theory. A way I simplify it for others is by framing it all as simple ratios vs more complicated ratios, and how harmony is a kind of alchemy in mixing those ratios together in the right amounts.

[+] wonger_|1 year ago|reply
I am very unfamiliar with the topic. Here's my takeaways from the article:

  - almost all music I've heard uses 12TET
  - JI is microtonal / an alternative tuning to 12TET
  - you're the author of the lovely ambient.garden, which uses JI
  - the audio widgets and visualizations were very helpful
  - JI has perfect harmonies, and 12TET approximates those enough to still sound good
  - JI opens up cool chord options
  - but there's extra pitfalls when making JI chords compared to 12TET 
  - still not sure what consonant, continuous, or misleading chords are. I only know what dissonance sounds like
  - still haven't looked at numbers; all I know is that there's ratios in there somewhere
[+] Sesse__|1 year ago|reply
My basic problem is that I'm really struggling to hear the difference between many of your samples :-) And I've already got a bit of experience with microtonality (DSP background, playing and have tuned multiple instruments, reasonable pitch perception). One of the big problems for me is that it's not so easy to hear them side-by-side; you have to stop one of them, then start the other (unless you want them both at the same time, which you probably don't), and both the start and stop buttons are pretty laggy. FWIW, most audio comparison tools I've seen (typically centered around compression or restoration) include some way of switching seamlessly between the two, without restarts.
[+] sonorous_sub|1 year ago|reply
I think you could make the piece more interesting to the casual reader by grounding the subject in its history. It's been suggested by the book below that the dominance of equal temperament in western music is a relatively recent innovation, something like 120 years old, and is perhaps a consequence of the industrial revolution and the demand for mass manufacture of musical instruments having uniform qualities it produced.

Further reading: How Equal Temperament Ruined Harmony (and Why You Should Care), by Ross W. Duffin (2008).

My layman's takeaway from the book: Equal Temperament is a compromise tuning that allows a piano to access all major and minor modes, at the cost of the keys on the outer ring of the circle of fifths to be somewhat out of tune. An ET "C Major" "sounds best", and the further you move away from it in either direction, the worse the key sounds. Also, the fact that Beethoven and Mozart were aiming for just intonation and/or meantone in productions of their works seems to be sort of an inside secret among music maestros, with rigid adherence to equal temperament slyly pushed on competing rookies to keep them trapped in the lower ranks by virtue of their resulting weaker performances. But the subject is highly contentious in western music for sure.

[+] bigstrat2003|1 year ago|reply
I would say that this is way too technical for me, however, I also only have the slightest hint of music theory knowledge to begin with. It seems to me like that isn't a problem though, because this is a very technical topic by nature.

Unrelated to the writing, but I was kind of disappointed that when listening to the examples, I cannot for the life of me hear a difference between just intonation and equal temperament. I know it's there, but I can't hear it at all.

[+] eltoxo|1 year ago|reply
I think it is a really great article but I am a chef too already familiar with the ingredients and style of cooking.

I think the main issue is getting people to try new dishes.

Of course, the dishes have to be good and not just the chef fooling around. Sometimes this style seems like "hey try this new exotic dish! It is made from mixing organic ice cream, grass fed beef, fair trade coffee and sriracha. Oh you think it sucks? Well that is because your taste buds are use to standard western food!"

I think of how no one needs an intellectual explanation as to why pad thai is good even if they only ever had pizza and burgers.

[+] iainmerrick|1 year ago|reply
Right now I suspect that I failed in the same way as my early readings did: this article might be hard to understand unless you're already familiar with the topic

I really enjoyed this article (although I already knew the core concepts, so I may be confirming your suspicion, sorry!)

The visualizations are terrific, especially the ones with the The Lord of the Rings chord progression. Despite knowing the concepts, I hadn't fully appreciated how TET forms a tiling; visualized that way, the "wrap around" the circle of fifths really hits home.

Excellent work, thank you.

[+] riemannzeta|1 year ago|reply
I will admit that I already had some familiarity with the topic, but I feel you did an amazing job at explaining specifically the constraints you're under as a composer, and in elucidating how having digital tools doesn't magically solve the problems you face in harmonizing in just intonation over the course of a piece. I had not really understood that before reading your article, and at least suspected that we might transition to hearing mostly Just Intonation eventually as digital tools became more widely used.

Of course you could make it more accessible by starting from some even more basic principles and elaborating further on those foundations, but then you risk losing some of our audience that's already familiar with those. For me at least you struck a good balance. (No pun intended!)

[+] thrtythreeforty|1 year ago|reply
Oh, and one last point of feedback - it wasn't apparent to me that the "Aníron" progression was walking across the lattice. You should make the projected versions semitransparent to show the main chord progression walking as it does in the JI lattice.

Still, awesome diagrams.

[+] jerf|1 year ago|reply
I really appreciate at the end how you explained some of why 12TET is so popular. There was a time when it was the new kid on the block, and there's a reason it took over. Most articles of this type are so busy taking a dump on it that you can't get a clear answer to that question.

I am a firm believer in the idea that if you want to know how to improve on something, you must clearly understand where you are coming from with current practice... and if your understanding of "current practice" is that it is entirely bad with no redeeming qualities, you don't understand current practice. We see that a lot in the programming space; there's a recurring set of ideas like "everything should be visually programmed everywhere!" that always come from people who spend a lot of time complaining about text without demonstrating any understand that it is there for a reason, indeed, many reasons, and if you casually throw all those good reasons away in your attempt to be new and fresh, you are starting so far to the negative that you stand no hope of producing anything new and useful.

Personally I really appreciate 12TET's ability to wrap the harmonies around as you show, and I've never thought about it that exact way, so I also appreciate the visualization. That doesn't mean it needs to be the only tuning used by anyone, though.

On to the music itself. One thing that I have found when I listen to a lot of "microtonal" music is that for music that is nominally more "consonant", it ends up with things I would not call "dissonant" per se (at least, in the traditional ways that 12TET has dissonant intervals), but a whole bunch of intervals I'd just call sour. Now, I won't deny that despite my general openness to alternate tuning pretty much everything I listen to is 12TET and I'm adjusted to that just like everyone else, but when I listen to Baroque-period music in pre-12TET tunings (as they were likely performed then), I hear the differences versus 12TET, but I don't hear that sourness in those pieces. It seems to me that if the goal is to seek greater consonance in tunings (and I acknowledge those who do not have that goal, this post is specifically about those who are seeking that) I would be hearing music that actually is generally more consonant. I would be more interested in alternate tunings if the resulting music was not so sour.

I really appreciate that your "ambient garden" is both different from what I'm used to hearing, but also I find it quite approachable. Sure, a bit of adjustment is necessary, or at least helpful, but it seems like one could actually argue that there is indeed greater consonances, and interesting contrast to conventional intervals, in that music, rather than just... sour intervals everywhere.

[+] pclmulqdq|1 year ago|reply
If I may provide some constructive criticism as someone who also has a background in tuning and tuning theory: I believe the article is pretty cool and you clearly have a good background on modern microtonal music. However, it is also clear that you do not have a good background on historical tunings (there are some factual errors in this regard).

Modern sources often implicitly assume that you understand tuning theory before teaching it, I agree. The understanding they often expect is this historical theory, though. I find that understanding historical tuning based on the idea of scales to be sort of tough to understand, while the circle of fifths is a lot more useful, and before 1900, pretty much nobody wrote about tuning in terms of scales since for all practical purposes it is very easy to hear frequency relationships in fifths and fourths rather than hearing them from steps.

Just Intonation is built on top of the harmonic series (not the circle of fifths), and I would suggest that you introduce the concept of the harmonic series before thinking about scales and fixed temperaments (your "boring" solution). As someone who does understand Just Intonation pretty well, I found the idea of going straight to a concept of scales very confusing, personally. The scale for true just intoned tunings is built on top of the harmonic series relationships you showed later, and those don't all have nice intervalic ratios.

Factually, the intervals were wrong for a typical Pythagorean scale: your fifth is 2^18/3^11 when the correct relationship for the typical notion of Pythagorean tuning is 3/2. Your scale stacks fourths based on 4/3 relationships, leaving the most important interval in the scale as the so-called "wolf" fifth. Most practical notions of Pythagorean tunings used fourths going one way and fifths going the other from the tonic, leaving the F#-C# relationship as the "wolf" (if the tonic is C), while all other fifths are pure. If you illustrate this with a circle of fifths rather than a graph showing scale degrees, it's a lot easier to understand. Pythagorean tuning also isn't really a type of just intonation since it doesn't use a harmonic series on a single note, but the exact definition of "just intonation" varies by source (some would say that even a temperament like Werckmeister is "just intonation").

All that said:

I would suggest you start with some ideas about tuning, introduce the harmonic series, introduce that "just intonation" is about preserving harmonic series relationships, and then go straight to your "freestyle" section. Eschew the notion that you need to understand the history of unequal temperaments to understand the present concept of the tension between the equal-tempered compromise scale and the just-intoned harmonic series.

Since you're more interested in modern theory, and your innovation and interests are there, I think you can skip the history and just get straight to the math and the lattices. Whether you use circles of fifths if you do this is up to you (I'm guessing you shouldn't - they are not so useful for modern tuning ideas).

[+] elevation|1 year ago|reply
For practical performance of alternate intonations, you can tune a guitar so that a particular chord shape presents perfect roots and 5ths, while arranging for a single string to be a perfect third (e.g, a few cents "flat" compared to equal temperament.)

When playing this same chord shape (or an appropriate derivative) up the neck, the relative intervals is maintained for other chords, allowing perfect intonation not just of the root chord but of other chords in the key family.

For chord shapes where a flatted string cannot be used as a 2nd or 3rd, it will sound objectionably flat, but for many chord shapes it's possible to fret the flat string with additional pressure to bring it back into tolerance.

Mastering this technique makes the guitar sound much more in tune with itself which is a wonderful sensation as a player.

[+] bwanab|1 year ago|reply
Aren't you still fighting the fact that the frets themselves are tuned as 12TET?
[+] kazinator|1 year ago|reply
Most guitars are not properly in equal temperament intonation, because that requires compensation at the nut.

In particular, an unwound G string can be off. I got sick of three decades of listening to that out of my main guitar, and earlier this year finally did something out of it with satisfactory results:

https://mstdn.ca/@Kazinator/112332540341043265

Without this string, I cannot get these G and D power chords to be in tune simultaneously:

G:

  E   |---|---|-*-|
  B   |---|---|-*-|
  G  o|---|---|---|
  D  o|---|---|---|
D:

  E  x|---|---|---|
  B   |---|---|-*-|
  G   |---|-*-|---|
  D  o|---|---|---|
If you tune the latter D, then the open G is too flat in the former G. If you sharpen the open G, the latter D is out of tune.

The problem is that when we fret the A note on the G string near the nut, it stretches; the string goes sharp. So the interval between the nut and that fret is wider than a tone, without the compensation that shrinks it.

The other strings have the problem, but the unwound G has it worse due to lower tension relative to mass. I'm so happy with the G compensation on that guitar, that it needs nothing else.

Anyways, there are videos out there which do A/B comparisons between ordinary guitars and just intonation. They feature uncompensated guitars, so they perpetrate a fallacy.

The guitarist must experience a properly intonated guitar with nut compensation first, then decide whether going to exotic intonations is worth it.

[+] cscheid|1 year ago|reply
(In case you didn’t know, it’s fun that) Jacob Collier plays a 5-string guitar in a tuning that takes advantage of this trick exactly. IIRC, from lowest to highest he tunes them a fifth, a fifth, a fourth and a fourth apart. By flatting the middle string a dozen cents or so, you can get a root-fifth-perfect tenth voicing of a major chord. Neat trick.
[+] naltroc|1 year ago|reply
Here are three additional references on applied Just Intonation.

The first book is abstracted away from composition and provides a more general description of tuning systems.

The next two are composition focused, explaining how tuning system is an option for musical works.

1) The book "How Equal Temperament Ruined Harmony" provides excellent historical context on why ET was a great solution and how we kind of got stuck with it.

While it could be read by anybody, having a bit of musical knowledge OR physics of acoustics knowledge may benefit you.

https://www.amazon.com/Equal-Temperament-Ruined-Harmony-Shou...

There are also two composers who recognize ET as a constraint (as opposed to the "the only option").

2) Harry Partch built many of his own instruments to circumvent issues from 12ET and composed music just for them. He describes his conceptualizations of JI in "Genesis Of A Music":

https://www.amazon.com/Genesis-Music-Account-Creative-Fulfil...

3) Paul Hindemtith also has some opinions on the matter, though both Partch and I disagree with his points of view. Nonetheless he has some at-the-time innovating ideas, some of which are valid and others of which may not have aged well. You can read about them in "The Craft of Musical Composition"

https://www.amazon.com/Craft-Musical-Composition-Theoretical...

[+] nonrandomstring|1 year ago|reply
Sometimes I like writing stuff in odd scales and intonations. The "Lucy" tuning is also very pleasant [0]. I once met a producer who had guitars fretted to this tuning. It doesn't lend itself well to DAWs that have an underlying MIDI note logic. Practically it's better to work in Pd/Max with raw oscillators and arithmetic than to try shifting MIDI note values around with bend. The ZynAddSub engine (also used in Yoshimi synth) has a nice scales filter.

Probably worth mentioning Jacob Joaquin [1] who did this stuff in Csound back in the 90s. On one of his patches I based a generative music system for a game, it was the "Harmonic tree" - very similar to the system in the article - repeated multiplication by integer fractions at each branch.

Using simple timbres (like flute/organ/sine) you can make big but crystal clear sounding chords, and then slowly changing one "note" at a time you get an ever evolving soundscape that blows anything "Eno" off the map. Its in a sweet creative area between composition and additive synthesis.

[0] http://www.harmonics.com/lucy/lsd/colors.html

[1] https://github.com/jacobjoaquin

[+] muhrizqiardi|1 year ago|reply
Haven't read it fully (to be honest this topic is new to me), but it's funny that as I read this article, I also happen to listen to a microtonal music: Flying Microtonal Banana by King Gizzard & The Lizard Wizard.

Both the name of the album and the name of the band sounds funny, trust me when I say this: It's one of the best microtonal album out there. They really mixed the sound element of turkish(?) music into the album. Highly recommended!

[+] Sharlin|1 year ago|reply
Should be noted that any ensemble that consists only of continuous-pitch instruments (eg. strings, trombone, human voice, fretless guitar) is free from the shackles of 12TET and its harmonies naturally tune to as close to "pure" intervals as the performers’ skills allow.
[+] sporkl|1 year ago|reply
Overall a good intro on the subject. I feel like at the start it might benefit from being a bit more explicit about pitches being frequencies and ratios being intervals; probably just worth a reminder for people who aren’t as familiar

Might be interesting to talk about how the usual ratios come from the harmonic series. For sounds that don’t produce a harmonic series, other potentially non-integer ratios can actually sound more consonant. The youtube channel New Tonality[0] has a bunch of great videos about this

Also wanted to mention that I’ve been working on a piece of commercial software[1] for working with freestyle/adaptive just intonation, if anyone’s interested

[0]: https://www.youtube.com/@new_tonality [1]: https://www.dmitrivolkov.com/projects/pivotuner/

[+] pierrec|1 year ago|reply
Thanks for posting this. The approach of keeping the traditional 12 notes while changing the tuning on-the-fly is really interesting and maybe the right tradeoff. This is so spot-on because adaptive JI is mentioned as a possible solution at the end of the article. It's the classic HN move where a weird topic is being discussed and someone says "why yes, I've made tools that happen to exactly match the niche topic being discussed!"

In fact, it's probably not my business, but this topic is so profoundly niche (and likely to remain so for a while) that I personally wouldn't make this commercial. My reasoning (and the reason I open-sourced some projects) is that it will limit adoption while changing almost nothing about my income. Obviously I hope I'm wrong, maybe these techniques will pick up in popularity. It's also possible that I think this way simply because I'm bad at marketing.

[+] thomasahle|1 year ago|reply
This reminds me of when I stumpled into a music theory flame war by proposing the "scale": 1, 15/14, 15/13, ..., 15/8, 2. https://music.stackexchange.com/questions/66620/what-is-a-te...

This set of 8 nodes (can be transposed to whichever base frequency) has the lowest common denominator between any pair of nodes among all 8-node scales.

I thought that might make it a good choice for a just intonation scale (which can really be any subset of frequencies you build you music from), but it turned out a sensitive subject.

[+] colanderman|1 year ago|reply
Oh hey, I've experimented a bit recently with the similar scale 1, 24:23, 12:11, ... 24:13, 2. Essentially a 12-tone version of yours. I've been calling it the "utonal" scale as it is a utonal [1] series. Complements what I call the "otonal" scale of 1, 13:12, 7:6, etc.

The trouble is, while intervals with the root are very consonant, arbitrary intervals don't sound great.

I've noticed though, that a utonal scale is very similar to the scale of harmonics [2], which is traditionally used relative to a moveable root note. So I intend to experiment in that direction.

[1] https://en.wikipedia.org/wiki/Otonality_and_utonality

[2] https://en.wikipedia.org/wiki/Scale_of_harmonics

[+] the_other|1 year ago|reply
Why is it a sensitive subject?
[+] rob7cc|1 year ago|reply
What a marvelous article about intonation and temperament. It is one of those expositions that approach perfection in conveying the subject matter. I am no music theorist but rather an engineer with an appreciation for all things wave- or signal-oriented. I will want to read it multiple times to savor the explanations. The author's album based on just intonation is linked in the article ("A Walk Through The Ambient Garden") and I highly recommend it: it is a mesmerizing composition.
[+] riemannzeta|1 year ago|reply
Readers who enjoyed this essay might also enjoy this one, which goes into further depth on the mathematics of musical intervals, the connection between the "blue note" in Equal Tempered jazz music, and more:

https://iopscience.iop.org/article/10.1088/0034-4885/72/7/07...

As an added bonus, the author draws an extended analogy between musical intervals and energy levels in quantum mechanics toward the end of the article, and indeed the study of the patterns in intervals between and among energy levels in the simple harmonic osciallator remains an active area of reasearch!

[+] vunderba|1 year ago|reply
When I compose, I usually begin by sitting quietly and humming or singing out loud until I have a melody that I like. Because I was born and raised in the west, acoustically I'm naturally accustomed to a 12 tone equal temperament.

Atonal music is more difficult for me to grok, and I kind of imagine that for you to be fluent and compose in these sort of microtonal scales you would need to be introduced to it at a young age - in much the same way that it's significantly easier to learn a second language if you grow up in a bilingual environment.

[+] andybak|1 year ago|reply
I'm no expert but your use of "atonal" and "microtonal" interchangeably here seems way off the mark.

"Atonal" usually refers to music composed without a fixed sense of key - and was originally used to describe music written using standard western 12TET.

It's a property of the music's relationship to key signatures - not it's tuning system.

[+] eternauta3k|1 year ago|reply
I have no clue about this topic, but isn't Just Intonation what e.g. people sing when left to their own devices?
[+] carterschonwald|1 year ago|reply
This is interesting, but the harpsichord based samples really made me not wanna listen. But that’s probably just me disliking harpsichord
[+] pierrec|1 year ago|reply
The choice of instrument is not entirely innocent. Harpsichords are rich in harmonics, and those harmonics are almost exactly multiples of the fundamental. This is perfect for revealing natural ratios in chords. Pianos have "bent" harmonics which would slightly obscure this. This is inharmonicity: https://en.wikipedia.org/wiki/Inharmonicity
[+] naltroc|1 year ago|reply
Would it be more appealing if we relabeled "harpsichord" as "pluck triangle synth"? :P
[+] crtasm|1 year ago|reply
If the author is here, the audio clips don't play for me. Firefox console has: Uncaught (in promise) TypeError: document.querySelector(...).contentDocument is null
[+] pierrec|1 year ago|reply
Sure, I also use Firefox but I don't have this error, so that's not really enough detail for me to look into it.
[+] riemannzeta|1 year ago|reply
I feel like I can hear beat frequencies in the 12TET chords that I don't hear in the JI chord examples.

Anybody else hearing that? Or is that my imagination?

[+] naltroc|1 year ago|reply
Yes!

We don't even have to listen to the audio examples to know that yes, ET chords produce beat frequencies. This is an artifact of the non-integer relationships created in ET chords that don't exist in the JI examples.

A piano will produce similar beat frequencies when playing a perfect fifth. Some ears are more sensitive to hearing it than others.

[+] hypertexthero|1 year ago|reply
One of the linked music examples, “occultation” by Pure Code, is beautiful ambient music.
[+] graycat|1 year ago|reply
When I started with violin, since my academic major was math, looked into the 12th root of 2 and ratios of small whole numbers, dissonance from beats, etc. stuff.

Then I learned (partly from a really good violinist):

(1) On violin, can use the ratios of small whole numbers to check intonation. So, get to check the intervals of octave, fifth, fourth, major third. That is, play two notes, each on its own string, together, listen for the beats, and adjust pitch (move a finger) until the beats go away.

That approach starts with the tuning of the violin, notes G, D, A, E, each on its own string, starting with the first G below middle C and going up by fifths (frequency ratio 3/2). The beats are easy to hear, and making the beats go away is what essentially all violin players do, whatever slightly different frequencies might come from other approaches to tuning.

(2) For the rest, there is a single, simple overriding principle: Make it sound good. Uh, there is no practical way to play a violin and get all the frequencies anywhere except close, varying with vibrato, and sounding good!

(3) The math of the 12th root of 2, etc. is too precise for violin -- can't expect to play frequencies to such precision and with vibrato, on that wooden box, with flesh fingers, real violin strings, bow rosin, etc. and really don't need to.

E.g., for the math, there is no good guarantee that a note played on violin is really accurately what the math and physics (a solution of a certain differential equation) define as a periodic function -- thus, lots of considerations of overtones start to become imprecise and, thus, moot.

Again, make it sound good! So, sure, for a major third, ratios of small whole numbers can be relevant, but for a minor third, mostly just guess at the semi-tone and make the interval sound good!

(4) For semi-tone guessing: The famous Bach E-major Partita starts with E (one octave above the open E string, half way along the string), D# (down one semi-tone), and then the E again. So, it's the three notes, played quickly, with the D# inserted and left quickly, with the musical effect an introductory bright heralding -- the relevance of the semi-tone as the 12th root of 2 is lost and instead just play the E with the little finger and for the D# squeeze in the next finger until it passes for a semi-tone and gets the heralding musical effect.

(5) For much more, can play the Bach Chaconne with its many chords, sometimes on all 4 strings -- no way can a violinist try to honor some precise tuning arithmetic for all the intervals played. E.g., the piece starts in D minor and with the "D minor" chord, that is, D, F, A. On a piano that would be the first D above middle C, the first F, that is, 3 semi-tones, above the D, and the A, a fifth above the D. But on violin that would have both the D and the F on the same string, so Bach put the F an octave higher, on the E string, a semi-tone above the E string. Sooooo, to play that opening chord, play the D and the A together, and, continuing right away all with one down bow, with the A and the F together. Then the F is from the index finger at a guess of a semi-tone above the E string. So, the bow starts on the D and A strings, both open (no fingers on the strings) and, thus, brilliant, and then both the open A string and the fingered F. So, the A and F 'would' be just an okay major third but the F is up an octave so that the A and F are an interval of 8 semi-tones and, actually, dissonant. Since the F is on the E string which is still brilliant even though fingered and not open, all three strings are brilliant, and the opening is dramatic and in a minor key. Some of the piano and orchestra arrangements make this first chord dramatic!

In all that for that opening chord, on violin, the 12th root of 2 and ratios of small whole numbers don't play a central role, and the same for the rest of the piece, nearly all chords.

Sure Bach knew very well what he was doing, indeed, in that music, SHOWING that could make music in all the keys, and had all those pages and pages, for violin, in another book, for cello, in another book, piano with the intervals and chords "sounding good".