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Polaris

What makes a chord follow poorly or well from another?

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I've been designing a computer program that learns what makes chordal motion sound good or bad, and I've had had a degree of success so far, but I would like to improve its performance as much as possible. To do this, I need to give it features to look for in progressions, features that help to determine how good or bad a progression will sound. Some of the features that I know affect the quality of a progression are the distance that the voices travel, what kind of motion they have relative to each other (e.g. contrary, parallel, similar, or oblique), whether dissonances are prepared, the absence or presence of parallel perfect consonances between pairs of voices, whether notes fall in each other's critical bands, and what notes follow the preceding notes. Beyond that, I don't have a whole lot of ideas. And so I pose a question that every composer should ask: what are the factors that make a two-chord progression sound good or bad?

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Just that..... common chords tones, uncommon chord tones(look up god chords), no parallel 5ths/ octaves, no hidden 5ths /octaves, contrary motion... stuff like that

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I gave some more thought to the question, and the broad answer, I think, is that almost anything you can say about a chord progression will play some role in determining how good it sounds. Virtually every characteristic you can think of will coincide more with either nice progressions or bad ones. So the question can be answered by answering the question: What are the properties that a two-chord progression can have? They can be very outlandish properties as long as they aren't 50/50 divided between producing a pleasant sound and a displeasing one.

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I think two chords is very little for a chord progression. Only if you have V - I will determine a tonality.

I also belive that even in tonal music, every chord can follow another one with success. It depends on the effect you want.

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On 8/16/2018 at 6:51 AM, Polaris said:

what are the factors that make a two-chord progression sound good or bad?

I think your thread title, and this question, are two different things.

Voice leading makes it sound "smooth", but smooth is not necessarily "good", which becomes increasingly subjective at a point.

The "good" aspect comes from the relationships between the chords themselves, and the between the chords and melody. The details of the former have been refined over centuries to the point that you can literally just use any progression that's been used before. The latter is as easy as looking to see what chord tones are present in the melody itself.

Every melody worth its salt implies a harmonic progression all by itself. 

Edited by AngelCityOutlaw

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I knew someone would say that it's subjective. I agree: it's subjective. That doesn't mean there aren't factors that help people decide whether they do or don't like a pair of chords together, though. Whether a shirt being lime green or not is a bad thing or a good thing is subjective. Its color nevertheless plays a role in helping people decide (provided they're not color blind).

When I say "chord" I mean all of the notes that are sounding. I'm not making a distinction between "the chord" and "the melody." Anything in the melody is a part of the sounding chord.

I disagree that it's a simple matter of using a progression that has been used before. Many progressions that have been used before sound bad to me. And music theory is very frequently helpless to explain why. Yes, it comes down to my subjective opinion. But what is influencing my opinion? And what things influence other people's opinions on a chord progression?

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9 hours ago, Polaris said:

I knew someone would say that it's subjective. I agree: it's subjective. That doesn't mean there aren't factors that help people decide whether they do or don't like a pair of chords together, though.

I didn't say there wasn't, in fact: I explicitly said why some work and others have told you as well.

Taken from the same key/scale/mode, common tones, leading tones, stepwise motion, relationship to the melody, etc. That's why the progression works.

Voice leading is about creating independence for the different lines that make up the chord and making changes to nearest note because it's easiest to sing. That's why it sounds smooth.

Further, can I ask exactly what the point of the program is? This is a very easy thing for composers to do all on their own.

 

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I have often written a melody to be played against another melody, using common tones, avoiding parallel perfect consonances, utilizing stepwise motion, etc. and ended up with a combination that sounds bad even though all of the standard rules have been followed and the melodies are strong individually. The purpose of this program is to figure out what kinds of features in a chord progression are correlated with bad effects of that kind so that I can avoid producing them in the future. A program that learns to produce consistently good progressions can tell me how to do it myself.

So far, in addition to what I listed in my original post, we just have sharing a scale and following the tendencies of leading tones. I believe there are more factors involved than that. In fact, I know there are, having investigated a few of them myself. It would be nice if people could try to think of some more things.

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3 hours ago, Polaris said:

I have often written a melody to be played against another melody, using common tones, avoiding parallel perfect consonances, utilizing stepwise motion, etc. and ended up with a combination that sounds bad even though all of the standard rules have been followed and the melodies are strong individually. The purpose of this program is to figure out what kinds of features in a chord progression are correlated with bad effects of that kind so that I can avoid producing them in the future. A program that learns to produce consistently good progressions can tell me how to do it myself.

So far, in addition to what I listed in my original post, we just have sharing a scale and following the tendencies of leading tones. I believe there are more factors involved than that. In fact, I know there are, having investigated a few of them myself. It would be nice if people could try to think of some more things.

 

This provides a bit more insight, and I think I can see where your frustrations and confusion are arising.

You don't need a computer program to teach you this, you just need to know the theory better. Namely: Modes & Levels, as well as chord tones and non-chord tones.

The first thing I think that's getting you is the assumption that two harmonies in succession, formed by interlocking melodies = a progression, but it does not necessarily. In doing so, you're probably treating everything as if it's a chorale, which isn't going to work if it's not a chorale. 

A chord progression is a shift of level that happens when one modal frame is temporarily contrasted against another.  So for example, a way that you could melodically think of I - IV - V - I in C, is not as C - F - G - C, but rather Ionian - Lydian - Mixolydian - Ionian. By stacking thirds on those roots, you then get chords. However, that progression is still implied just by those root notes alone.  

Two or more melodies may vertically create triads themselves, but this does not mean the progression has changed, and I'm about to demonstrate why:

This is one of the most famous themes in recent times:

MpFZrfG.png

The Harry Potter theme. Except in the actual score, it's harmonized like this.

mICu96r.png

The top note is the melody, and the bottom two are harmony parts and it's all played over the root note in the bassline. You'll notice they are nothing but parallel movement. In fact, when the triads are kept in the same position like this and moved chromatically, it's called "planing" and John Williams uses it extensively. Let's take a closer look at the first figure, which is all played over a single A note in the bass.

Qj3F8eo.png

I've highlighted the non-chord tone here in the first bar. Specifically, this kind of non-chord tone is called a "neighbor tone" because it neighbors (chromatically in this case) the chord tone.

Now watch what happens when I bring back the harmony parts to the melody:

mICu96r.png

Three neighbor tones at once instead of just one. You could play this over the full A Minor chord and it would still work just as well. You could keep harmonizing the melody like this (and Williams does) for the entire progression and it would still work. It's just harmonizing the melody in thirds downward, and emphasizing chord tones of the current underlying chord in the progression. 

This is not like a chorale, where how many tones the human voice can leap, and how quickly, are limited. Thus, in such a case, each new note is often the next chord in the progression or at least a chord tone, and the voice leading is there to make the smoothest transition and ensure that it's easy to sing; the top voice is the melody, like so:

gxOk9rw.png

I hope this helps!

 

 

 

 

Edited by AngelCityOutlaw

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Thank you for your response. My problem, though, isn't that I regard everything as a chorale. I'm looking at what makes two harmonies ("harmony" is probably a better word than "chord," simply because the word "chord" comes with so much baggage, like people thinking of there being a distinction between "the chord and the melody" or classifying certain tones in the chord as "non-chordal," neither of which affect my considerations one way or the other) in succession sound good or bad in any context, including in the type of situation that occurs in the Harry Potter theme. Yes, I know that some notes (and sometimes even whole chords if it suits a theorist) are typically classified as non-harmonic, and I'm familiar with the usual figures like suspensions, neighbor tones, and so forth. Such devices are all changes of harmony. That's what I'm looking at--changes in the overall sound.

On a side note, I have to disagree with the idea that only the top part has melodic implications. All of the intervals that occur in the progression, including those created by the difference tones, have melodic significance. The upper part may be more prominent, as is often the case, but the other horizontal (and diagonal) connections between the notes are heard to some extent as well.

Edited by Polaris

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It's all about voice leading and the voicing of the chord.  

Literally and chord can be followed by any other chord and it can sound good. ... it can also sound terrible. With poor voicings, even a ii - V - I can sound gross.

 

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4 hours ago, robinjessome said:

It's all about voice leading and the voicing of the chord.  

Literally and chord can be followed by any other chord and it can sound good. ... it can also sound terrible. With poor voicings, even a ii - V - I can sound gross.

If it were "all" about voice leading, 99% of rock music, a significant amount of guitar music in general, or basslines consisting solely of root notes would sound terrible — but they don't. I think a lot of people here are thinking smooth motion is synonymous to "good", which is a bit of a mistake. 

Honestly, this just isn't rocket science. Examine your melody and pick out the chord tones, take the scale and make an 8 bar bassline consisting of root notes and go from there, examine existing scores and find out what progressions they used that you like; how many film scores don't use the same chromatic-mediant changes? 

Edited by AngelCityOutlaw

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