PG Music Home Forums General Discussion Woodshedding - Learning to Play! What exactly is a Tonal center vs. an underlying Mode or Scale on which a song is based ?

Hi all,

I'm not sure if these terms are identical, or change depending on context, but is there a difference between:

1.) the "Tonal Center" and the "Tonic" - are they one and the same
2.) the "Tonal Center" vs. the underlying Scale or Mode a song is based on ?

And when is writing a 'song' or piece in C major, then changes to C minor, is this a modulation, or a change in tonality, or a change in key, or a change in tonal center ? How is this type of change described accurately among trained musicians ?

Thanks in advance,
Joe V.

"How is this type of change described accurately among trained musicians ?"

This I was thinking about last night. Firstly, I don't think 'trained muscians' if you mean pro musicians really bother too much about the difference and could use the terms interchangeably, but this does not mean there is not a difference.

I think tonal centre and Tonic are one and the same.

Secondly the word mode means something completely different today, than it used to Jazz modes you probably know, but "Church" modes are different, some of them do fit into this system but some don't. Modes existed before the major/minor scale came to predominantce.

These things only matter if your say, programming a Gregorian Chant, or if you want to mess with your thinking on Giant steps (lol)

Anyways here is a link that does a decent job of going into the minutae

http://music.stackexchange.com/questions/6401/whats-the-difference-between-modal-music-and-tonal-music

This music dictionary I find very comprehensive and useful for this sort of question, I have to use Chrome to get it to work though.

http://www.dolmetsch.com/musictheory31.htm


Z

Changing from C major to C minor is a modulation C minor is the relative minor of Eb. A modulation is a change of key. Note: This does not always mean a change of key signature. There are mini modulations in many songs without the key signature being formally rewritten, instead a few (so called) 'accidental' sharps or flats are used. This is often done when the intention is to quickly return to the original key signature of the piece.

Changing from C major to C minor is also a change in tonality between the 'major tonality' and the minor 'tonality'. This would be the popular answer.

I would see a 'tonality' as a function of pitch collection - the aural feel of its sound. That is, you first gather yourself a group of notes (randomly if you wish). Order these notes from low to high in a series - you have a 'scale' of sorts. Start from the nth position on this scale and go round the series - in my book this is a 'mode' of the scale you just created. If you were then to impro a song using these modes, these modes would share a 'tonality', the tonality of the pitch collection.

If you think in major diatonic harmony, there are actually three modes that would be considered 'minor' - Dorian, Aeolian, and Phrygian. See my explanation of the Lydian Chromatic Concept (Russell) for reason why these occur in their specific places.

These modes are all commonly called 'minor' simply because they all share the minor chord form: Root, minor third, perfect fifth, flat seventh. Actually they are very different scales (and therefore different tonalities) you find that the sixth and the ninths vary in a structured way. All these minor modes occur within the diatonic structure of the modes of a major scale.

There are also two other scales that are considered 'minor' - by convention. These are the melodic and harmonic minor. Both of these scales possess root, minor third, and perfect fifth. This nomenclature is a matter of Western Classical tradition, or more specifically the Common practice period.

It is said that it was popular practice for a minor scale to have its seventh raised to accentuate the pull heard to the tonic. If you do this with a Dorian Mode minor scale then you get the melodic minor, if you do this with an Aeolian/Relative minor you get the harmonic minor.
Often this device was used only when ascending to the tonic, it was felt it was not required when descending - so the story goes. Eventually this all morphed into some kind of tenuous (IMO) theory. Of course this is only really a historical narrative and each composer thought their own way about it. It's useful to bear in mind that historically, first comes the practice - the emergent, often nebulous, convention, then after comes the codification and the naming systems.

Jazz reframed a lot of all this and developed it's own way to use these terms. In particular, the term melodic minor is used in Classical Music (mostly) as having two forms, an ascending and a descending form.

The ascending melodic minor scale can be notated as
1 2 ♭3 4 5 6 7 8

While the descending is:
1 2 ♭3 4 5 ♭6 ♭7 8 (same as Aeolian or unaltered minor)

In jazz the melodic minor is the same both ascending and descending it's the top form above.


Both the Melodic minor and the Harmonic minor (which are not modes of the major scale), have the potential to create their own modes, in jazz the melodic minor in particular is used this way.
The modes of the harmonic and melodic minor do not have specific names, so the modes are thought of as second mode, third mode etc.

If you want to spell a chord for one of these modes then you get those complex looking chord names such as C7#9b13. Note the reason it looks so complex is not because it IS complex, its just because the notation system we inherited is based on the Ionian Mode of C, which has precious little to do with this particular chord. Its bashing a square peg into a round hole.

No wonder everyone gets confused!

Its my opinion that Notation actually adds to the confusion a musician experiences when trying to understand these things. It all starts with those Monks with leaky quill pens that drew eleven lines (one for middle C eventually disappears) and then scratching blotches on or between the lines. Since then various disparate parties have cobbled together various compromises which were made to work. Especially in the times where we have computer screens with full colour and the ability to hide and reveal features, there is room for a complete rethink of this system IMO.

So, in summary

There are three minor chords in the major scale tonality - Dorian, Aeolian, Phrygian. The relative minor (Aeolian) is most frequently used as a key centre in its own right.

The melodic minor is also used in jazz as a key and its good to be familiar with its modes.

The notion of a minor is very broad. If you see a simple minor chord symbol it means a chord which shares the following form root, minor third, perfect fifth and flat seventh. Its almost always Phrygian, Aoelian, or Dorian in its function.

In reality the modal scales and the derived chords of a major scale get darker in this sequence:

4, 1, 5, 2, 6, 3,7 (Lydian, Ionian, Myxolydian, Dorian, Aeolian, Phrygian, Locrian

If your ear equates major third type chords with bright sounds and minor third with sadder darker sounds, then there is a case for claiming the Locrian is a minor 'sound' but it lacks the perfect fifth. Usually the locrian and the dominant seventh chord are gtreated as special cases.

There is a very interesting relationship using root and first inversion triads, where major sounds become minor (and vica versa) whereas Dominant 7th chords in first inversion become locrian: Maj/min, Dominant7/locrian. What is interesting about this to me is that majors exist within minors and vica versa. Its a very effective device playing minor over major without dischord.

Perhaps this is enough for today though, it takes a relaxed mind and a coffee to ingest these ideas

Z

wow ! Much of what you say is consistent with what I have learned - I think. Thanks for taking so much time to write this out.

Good questions - get me thinking

Z