Please help me because I'm very stupid and my brain hurts.

I've been trying to make sense of the explanation of what constitutes consecutive fifths and octaves, and why/how to avoid them in both Harmony in Practise and my ancient copy of the little red theory book. Both the explanations are basically the same, but I am having trouble recognising them.

I understand that it is the interval of a fifth or an octave in a chord, and that you should not have 2 (or more) in a row - but how can this be avoided given that in 4-part harmony you must double something from a triad, thereby creating an octave on every chord? Is it simply that 5ths/8ves between the same 2 parts must not be consecutive? So you can have a 5th between Alto and Soprano parts, followed by one between Tenor and Bass parts - but not another consecutive A/S 5th? And also, does it still count as a fifth or octave even when separated by another octave/s (eg, low C to high G)?

As you can see, I'm not grasping this very well. Sorry if the above makes no sense at all, it's a symptom of my state of mind! Hopefully some kind person can untangle me.

Actually you have grasped it well, Fred. Consecutive fifths and octaves should not occur in the same two parts. The easiest way to avoid them when writing four part harmony is to get the outer parts moving in contrary motion, and to keep notes common to more than one chord in the same part.

I've been struggling with this too. Its taken me a phenomenal amount of time to work it out but I have found switching between different work books helpful. I started with the ABRSM Grade 6 book which I couldn't cope with as it assumed you had a certain amount of knowledge (or it was well hidden in the text!). I then bought The Big 6 book which was easier to understand. I personally have found the Josephine Koh Grade 6 book much easier to understand used alongside a book called Guidelines on Figured Bass with exercises by Eric McDonald and Chan-Chiu Lu Yah. I've also got the Harmony book from the same series but I haven't opened it yet!
A probably very obvious tip (but it didn't occur to me for a while) is to buy a manuscript book and try different solutions out. I also follow the method of putting in the bass and soprano parts in contrary motion and then filling in the inner parts. I bracket all 5th and 8ves on the staves and then it is easier to avoid consecutives between parts. I've also read not to have an interval of more than an octave between the alto and soprano parts. I guess in the end there appear to be so many rules there can't be too many solutions to each question. I suppose I'll get there in the end.

There should not be an interval greater than an octave between any parts other than bass and tenor really. Woeking several solutions to each exercise is a good idea. Play them through afterwards too, to see which actually sounds best and then try to understand why one works better than another
Then go away and listen to some plainchant and forget all of the rules.

Thanks so much for these replies, this is just what I needed to know! I've been hmming and haaing over this for days, and all I needed to do was ask in the Clever Forum. Thanks, clever forumites!

I think that the hardest ones to spot are those between the parts that are not next to each other like sop and tenor or alto and bass.

If in real doubt, double the third. It may seem repeatitive when you are writing music, but dont take any risks if you are in an exam situation, unless you are feeling saucey!

I was taught that doubling the 3rd is something you DON'T do in a major chord.
Try doing it and play it..... it sounds wrong.

But but.... if you got your root note in the bass, your root note proberly again somewhere else repeated, then you got the the fifth, and the third. The third tells you prodominately which key, and which chord that it is. It is the most important note in a triad. It doesnt matter weather or not it is a major or minor! Makes no difference.

Don't know all the ins and outs of it too well, I just know that you don't omit the third (as you say it defines the chord) and in a major chord you don't double it either though it's ok to do so in a minor chord.

It may well be the most important note, that doesn't necessarily mean it's OK to double it.

It's been a long time since I did proper harmony, but as far as I remember I remember the same as sbhoa, that one should not double the 3rd in a major key (unless one is Bach and a genius! )

Just a sec, I read up on this last week. Here it is...

From Harmony in Practise by Anna Butterworth (suitable for grades 6-8 AB theory), p.20:

The 3rd of the chord is normally included. The doubling of the major 3rd produces a characteristic, rich sound. Although is was doubled extensively by Bach (for example in his chorales) it is best at this stage to double the major 3rd only when it is two octaves apart. However, it should not be doubled if it is the leading note (in chord V). Doubling minor 3rds is acceptable.

So, it is sometimes okay to double it, but perhaps easier to just avoid doing so in major triads. I think.

You could always use Chord Ib (or whatever ...b) as well.

Double the third in minor chords only, not in major chords, at least when you are a learner. A chord may be written without its fifth but it is not good standard practice. There are times when it can be useful to avoid consecutives but usually you will get a better result if all three notes are sounded. Double the root or the fifth in major chords. In minor chords doubled third is fine.

Use the term 'parallel 5ths' rather than consecutive - this better explains what you need to avoid, i.e. a 5th between two parts moving either up or down in parallel with one another towards the next chord.

Always double the root if possible, then the 5th, and only the 3rd as a last resort if you can't avoid parallels.



[pedant]

As an aside, while the 3rd does indeed define the difference between Major and minor, the harmonic series places the 5th before the 3rd, so you could argue that the 5th is more important...

[/pedant]

The harmonic series is often used to "explain" the perception of consonance and dissonance, but modern acoustic research has shown that real people hear things in a way that is not predicted by this simple theory. Schenker used the harmonic series to underpin his analytic theories, but his argument is severely flawed. To most people a 1 3 8 chord sounds richer and better defined than a 1 5 8.

Hi all. This is what i learnt from my teacher and i think it explains quite well..

Intervals of 5ths and 8ves are considered thin texture in the perspective of the Baroque Period ppl. So they tend to avoid playing them too many times hence consecutive 5ths and 8ves are avoided at that time of study (or ppl call it parallels 5ths and 8ves). In actual fact when you have a 5th to an 8ve in parallel motion, it is also considered as a "fault" (not good progresssion) becos both of them are thin texture. So like all others who mentioned here the best is to move them in contrary motion.

hope this helps a bit more..