Q: Piano Keys

Cafe Society
1

I was looking at a poster explaining music theory for piano, but I don’t get a few things:

a) Some keys have a note deemed flat-flat. In other words, it is a note with a superscript “b” and another superscript “b” above that! What the heck is a flat-flat? What does that mean? And, is “flat-flat” the proper term? (I made the term up, but maybe someone knows the correct name for this.)

b) Also, some notes within a key, such as the key of C, are deemed both a flat and a sharp (such as D#/ Eb); yet, other notes only have one designation, like A#. But, why wouldn’t it be shown as A#/Gb?

  • Jinx
2

Any sharp raises the note by one half step, while any flat takes it down by one half-step. C-flat is B. I can’t speak for what your poster says.

A double flat takes the note down by two half-steps instead of one. For instance, Abbis really G. This is typically seen only in pretty complicated music… the reason for doing this, rather than just writing the note as a G, is that the G may already be “flatted” in the key signature.

I’m doing a crummy job describing this, but hopefully you get the idea.

3

a) What you’re referring to is a double flat. It’s just one whole tone below the original note. So, a Gb, for example, is the same thing as an F. There’s also a double-sharp, the symbol for it looks like of like a 4-leaf clover.

b) Well, A# would be the same key as Bb, and Gb the same key as F#. But generally, it depends on what key you’re in. To take a specific example, if a D major chord appears in a piece written in C, the third tone of that chord is going to show up as an F# rather than a Gb. This is because you’ve taken a chord in the key of C (d minor) and altered it by raising the third. The note you’re playing isn’t a lowered G, it’s a raised F.

It gets more complicated than I can explain. On a piano, you’re right, any key can represent several different notes (for example, the key that plays a G could also be written as F## or Abb), but that’s only because of equal temperament tuning. In Bach’s day, an A# was NOT the same as a Bb, and he could have told the difference. IIRC, equal temperament did not become universal until well into the 19th century.

4

Actuall it was Bach who brought around equal temperment with his “Well Tempered Clavalier”. Arguealby the most important work in western music.
A composer may write something as a double flat to make it less complicated when writing a passage like

A-flat B-double Flat, C. He could write out A-flat, A-natural, C, but the two A’s in a row may be confusing to the player.

Also, technically, when analyising the chords there is a difference between an A-double flat and a G. (not to ears mind you, or what actual key you hit on a piano) CEG is a C major chord, C, E-flat, G is a C minor chord. C E-db G is something else. CDG could be a D-7 chord with a double flat five, and an omitted third.

If that makes any sense to you, then you probably already understand your question so this wasn’t useful at all was it?

5

Exactly. :smiley:
Here is a Wikipedia article on equal temperment. To understand it from scratch, however, you’d have to click on every link in it. About halfway down is a great chart with the percent difference from just intonation, where notes are based on fractions. (An octave is 1/2, just look at a guitar). The problem is that the fractions for, say, Gb and A# aren’t the same, and Gbb isn’t the same as A.
On a piano, it’s all evened out so that they are the same, but instruments that aren’t equally tempered, like a harpsichord, it’s very often different. This also means those instruments can pretty much only play in the key they’re tuned to, where a piano can change key simply by shifting up or down.
BTW, the symbols are called accidentals, and double-sharp looks like an “x” not “##”

6

I think I follow you, but I wonder: If you say the Gb may already be in the key signature, then isn’t a regular “G” denoted by a “G” with a “natural” symbol next to it? I thought the convention was to use the natural symbol when a note is an exception to the key signature…when the regular key is intented to be played in a specific instance. - Jinx :confused:

7

Except that the Well-Tempered Clavier was in well-tempering, not equal-tempering. Equal-tempering didn’t achieve wide use until the 19th century. Different key signatures would still have had subtly different sounds.

8

Some keys (musical not piano ones!) and scales require double sharps. A scale only has one note of each letter name, so a G sharp minor scale goes:

G# A# B C# D# E# Fx G#

The E# is played on the piano with the F key, and the F double sharp with the G natural key.

It depends on two things. Firstly the practicality - if there’s a passage which alternates between these two notes, having flats and naturals all over the place clutters the visual appearance of the music, whereas Gb/Abb would be easier to read as there’s not so many accidentals and it retains the visual up/down representation on the page.

The second reason for choosing particular accidentals is how it fits into the harmony. If the note is part of a diminished harmony on Bb, then it needs to be Abb. But we won’t go too far down that line :wink:

9

(…G# melodic minor scale…)

10

Look at the key signatures here:

Ab major: Ab Bb C Db Eb F G Ab
Eb major: Eb F G Ab Bb C D Eb
Bb major: Bb C D Eb F G A Bb
F major: F G A Bb C D E F
C major: C D E F G A B C
G major: G A B C D E F# G
D major: D E F# G A B C# D
A major: A B C# D E F# G# D

Note that we do not write A major as A B Db D Fb E## Ab A.

Technically, those notes are enharmonic with — they sound the same as but they are spelled differently than — the notes of the A major scale. However, that awful notation is confusing: F has a lower pitch than E, D and A are used twice, and C and G do not appear at all.

A good key signature means that each note of A B C D E F G is used once and once only in the scale, in that order, of course starting over at A once you go past G.

If you didn’t quite follow before, I hope that covers it, because now we’re moving on:

You ask “if they mean you to play G, why don’t they just say G natural?”

The answer is: well, it looks like a G if you’re staring at a piano keyboard, and it sounds like a G, but it may not be a G. Yeah, that’s the piano key you’re pushing down on, but it ain’t necessarily called G in this particular time and place.

(Yeah, GorillaMan, I’m gonna go there. It’s 4:30am and I’m feeling brave.)

Musical intervals and chords have proper spelling, just like English. Just like “bow” and “bough” sound the same but mean different things, and “ship” and “boat” mean the same thing, but have two different spellings, music has those distinctions too.

I already defined enharmonic: sounds the same, spelled differently. Here are some intervals. Spot the enharmonic ones:

major seventh: C to B
minor seventh: C to Bb
diminished seventh: C to Bbb
major sixth: C to A
minor sixth: C to Ab
augmented fifth: C to G#
perfect fifth: C to G
diminished fifth: C to Gb
augmented fourth: C to F#
perfect fourth: C to F
diminished fourth: C to Fb
major third: C to E
minor third: C to Eb
augmented second: C to D#
major second: C to D
minor second: C to Db

The thing is, you can’t know what an interval is just by looking at the piano keys: you gotta see it in the sheet music. By definition, C to A is a major sixth because it is the inversion of A to C, a minor third. (Major always inverts to minor.) By definition, C to Fb is a diminished fourth because it is the inversion of Fb to C, an augmented fifth. (Diminished always inverts to augmented.)

Sixths always invert to thirds, and vice-versa; fifths invert to fourths, and vice-versa; seconds to sevenths, etc.

You can build chords off of intervals, namely the interval between the first and second note, and the interval between the second and third note:
major chord = major third + minor third
minor chord = minor third + major third
diminished chord = minor third + minor third
augmented chord = major third + major third

Therefore they’d use Abb instead of G because you’d use “bow” instead of “bough.” That’s just how it’s spelt.

11

Psst. No they’re not.

I think you meant G# and Ab are enharmonic — not Gb and A#. Also, you probably meant that Abb and G were enharmonic too, not Gbb and A.

:slight_smile: