When can we say a given scale has a tonal center?

Question

I have started studying music theory recently and I stumbled upon the concept of scales.

The way I understand it (please correct me if I am wrong):

It can be difficult sometimes to create a good harmonization between the melody and the rhythm if we include all of the existing 12 notes into a piece. Thus when a composer wants to compose a piece, he generally wishes to select a subset of the 12 existing notes and decides that his piece would mostly include only these notes. Thus the notes that he selects for his piece collectively form a 'scale'.

So basically, if my understanding is correct there can be many varied types of scales that can be formed. They can serve different purposes as each scale would have a very different flavor and mood attached to it.

I was then introduced to the concept of a tonal center: one note of your scale can be emphasized and it would pretty much act as a 'central point' around which the entire piece would seem to revolve about.

Now this was a very intriguing concept. But as I dived deeper into the topic, I got to know that there exist scales that do have a pretty well defined tonal center- such as the major and minor scales and their different modes.

But along with those, (since a scale is just a selection of notes from the existing 12 notes) there can also be scales defined which practically do not have a tonal center- such as the whole-tone scale or the chromatic scale.

One observation I was capable of making was that the major and minor scales are constructed with a combination of whole steps and half steps, i.e. the notes are differently spaced. I think this is one of the features required to have a tonal center.

As for the whole-tone scale or the chromatic scale all the notes are equidistant. I guess it becomes monotonous and our brain is not able to settle on one particular note as the 'home-base'. Or maybe scales with such a symmetric construction cannot have a tonal center. These are just some theories I came up with after some thought and observations, which maybe be completely wrong, and they also lack a logical and concrete explanation backing it.

Hence I thought let's just jump a step back to a much more fundamental question. I was looking for maybe a more informative explanation as to why a scale even has a tonal center. What is the music theory involved behind any scale having or not having a tonal center? If I want to create a new scale for my piece suppose, what must I keep in mind while selecting notes, to make it have a tonal center?

What are some necessary features in a scale's construction for it to have a tonal center? How to look at a scale's construction and comment about if it can have a tonal center or not?

For example: Can the wholetone-halftone scale have a tonal center?

(It is an octatonic scale and constructed as such: W H W H W H W H )

I am very new to the music world, it's been a little more than 6 months now to be precise. Kindly help me with these questions that have been clouding my head since quite a long time now. It would keep me motivated :) .

Thank you in advance!

Answer 1

Tonal center is a name of the note that "feels like home". If you can name such note, then it is the tonal center. But you can use many different chords and scales in a single piece, while still maintaining the same tonal center.

A very simple example: you have a progression in C major, you use C ionian scale, but when the dominant G chord comes, you switch to G altered scale (G Ab A# B C# D# F). G altered doesn't even contain note C, but does it mean the tonal center changes? No! The root of the chord is G, but it produces a tension you want to resolve to C.

when a composer wants to compose a piece, he generally wishes to select a subset of the 12 existing notes and decides that his piece would mostly include only these notes. Thus the notes that he selects for his piece collectively form a 'scale'.

I don't believe this is accurate. You can find many examples (in particular in jazz and in styles borrowing from jazz) that don't stick to a single scale, that modulate often, yet still have a well defined tonic.

You certainly can base your composition on C whole-half scale, and make it feel like it's in C. On the other hand you can take notes from C ionian scale, and play them in the way that F feels like the tonal center... in which case it would be more accurate to say you use F lydian.

Answer 2

One possible approach to this is exactly what you mentioned in your post: to recognize the inherent asymmetry in tonal music. The perfect fifth, for instance, does not split the octave in two, but rather just barely misses it. Same with the major triad: the third doesn't split the perfect fifth in two, but it just barely misses.

So one of the ways in which a scale is able to create a sense of a tonal center is by the inherent asymmetrical structure of the scale. This is often done by constructing the scale with different intervals (like half and whole steps) and by arranging those intervals in asymmetrical ways (like WWHWWWH as opposed to HWHWHWHW).

The corollary to this is that perfectly symmetrical scales do not have any inherent tonal center; if you were to play a chromatic or whole-tone scale, you would sense that either a) no pitch feels like a tonal center, or b) all pitches feel equally like a possible tonal center. In music based on these scale collections, other aspects of the piece have to help the listener determine what the tonal center is.

With all of that said, other aspects of the music can help suggest a tonal center no matter what scale collection is being used (if it's even just a single scale collection, which is very very rare). Extremes of register (i.e., the highest and lowest pitches) can help point towards a tonal center, extremes of dynamic, metrical emphasis, the lengths of held pitches, etc., can all suggest a tonal center, even in asymmetric collections like the whole-tone and chromatic scales.

Answer 3

I think you've already pointed in your question to one reason that a scale can have a tonal centre: because we're free to simply define it as having one. People are free to talk about the D chromatic scale, for example - and it might be entirely sane to describe the tonality of a piece as 'D chromatic', in some cases.

The reason why a particular scale might have a subjective sense of tonal centre comes down to the relationships between that central note and the other notes in the scale. One reason that the major scale has such a strong sense of tonal centre is that the tonic is accompanied by the major third, perfect fourth, perfect fifth, and major sixth - all notes that have a strong sense of consonance with the tonic. And as Tim says in the comment below, one of the notes that is very dissonant with the tonic is the 'leading note' a semitone below. So the major scale can create a sense of consonance with the tonic, and also of 'leading in' to it.

And yet - if we consider the modes, we realise that the exact same same interval pattern could have a number of other tonal centres, if we use phrasings in the music that emphasise those instead. This speaks to the fact that when it comes to scales, tonal centre really is partly just a question of definition, as well as a question of perception - and, leading on from that definition, an expectation of how we expect the scales to be used. C major and D dorian have exactly the same notes in, so we can't really say that that set of notes suggests one of those tonal centres and not the other. However, if we've defined the scale as D dorian, we're expecting those notes to be used in phrasings that gravitate towards D.

Answer 4

Following the theory by Schenker a “train” of a 5th 54321 or octave 87654321 or a triad 531 defines the tonal center, no matter if minor or major or any other mode.

Urlinie in relation to the tonic triad. The fundamental line (German: Urlinie) is the melodic aspect of the Fundamental structure (Ursatz), "a stepwise descent from one of the triad notes to the tonic" with the bass arpeggiation being the harmonic aspect.[3] The fundamental line fills in the spaces created by the descending arpeggiation of the tonic triad. Its first tone (primary tone, head tone) may be scale degree 8, scale degree 5 or scale degree 3.

There are no tonal spaces other than those of scale degree 1—scale degree 3, scale degree 3—scale degree 5, and scale degree 5—scale degree 8. There is no other origin for passing-tone progressions, or of melody.[4]

https://en.wikipedia.org/wiki/Fundamental_structure