i vaguely know that a key is a set of notes but do they always have to sound good together? who created these keys and what criteria do a set of notes have to have to be considered a key?
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Traditionally the way that we came up with the musical notes was based on ratios between frequencies – for instance two different C notes one octave apart have an exact ratio of 2:1 between their frequencies.
It turns out there are other ratios of frequencies that our ears find pleasing, like a ratio of 3:2 (or at least very close to it,) and we call that a perfect fifth. If you play C and G together (in the same octave,) their frequencies have a 3:2 ratio and they sound nice together.
That’s essentially the concept of keys, it’s a bunch of notes with pleasing pitch ratios that sound nice together.
Traditionally the way that we came up with the musical notes was based on ratios between frequencies – for instance two different C notes one octave apart have an exact ratio of 2:1 between their frequencies.
It turns out there are other ratios of frequencies that our ears find pleasing, like a ratio of 3:2 (or at least very close to it,) and we call that a perfect fifth. If you play C and G together (in the same octave,) their frequencies have a 3:2 ratio and they sound nice together.
That’s essentially the concept of keys, it’s a bunch of notes with pleasing pitch ratios that sound nice together.
Traditionally the way that we came up with the musical notes was based on ratios between frequencies – for instance two different C notes one octave apart have an exact ratio of 2:1 between their frequencies.
It turns out there are other ratios of frequencies that our ears find pleasing, like a ratio of 3:2 (or at least very close to it,) and we call that a perfect fifth. If you play C and G together (in the same octave,) their frequencies have a 3:2 ratio and they sound nice together.
That’s essentially the concept of keys, it’s a bunch of notes with pleasing pitch ratios that sound nice together.
There are a couple parts to this question, and there are both historical and mathematical reasons that keys are as they are today.
>do they always have to sound good together?
If you played all the notes in the key of C major at the same time, it wouldn’t sound good, but I think you mean “do the notes in the keys always have to work well together.” The answer is yes, because every major key is built using the same blueprint as every other major key. D major contains the same gaps between notes as F major or Bb major or E major, but it just starts on a different note. Similarly, every minor key is built using the same blueprint as every other minor key.
>who created these keys
I’m no expert on music history, so my understanding is limited in this regard, but I believe the major scale and its modes were established as organizations of pitches to be used in Gregorian chant music in the Middle Ages. Now, the more interesting question is “how did we decide on that collection of pitches” and that leads into the more mathematical side of music, which I can elaborate on if you’re interested.
> what criteria do a set of notes have to have to be considered a key?
Generally, if a set of notes form a major or minor scale, then the music written using those notes is said to be in a major or minor key respectively. However, this is only part of the picture, because you may notice that there are major and minor keys that contain the same selection of notes (like C major and A minor, for example). The other part is based on the tonal center: whether or not a song is in the key of C major or A minor depends on whether C or A “feels like home”.
There are a couple parts to this question, and there are both historical and mathematical reasons that keys are as they are today.
>do they always have to sound good together?
If you played all the notes in the key of C major at the same time, it wouldn’t sound good, but I think you mean “do the notes in the keys always have to work well together.” The answer is yes, because every major key is built using the same blueprint as every other major key. D major contains the same gaps between notes as F major or Bb major or E major, but it just starts on a different note. Similarly, every minor key is built using the same blueprint as every other minor key.
>who created these keys
I’m no expert on music history, so my understanding is limited in this regard, but I believe the major scale and its modes were established as organizations of pitches to be used in Gregorian chant music in the Middle Ages. Now, the more interesting question is “how did we decide on that collection of pitches” and that leads into the more mathematical side of music, which I can elaborate on if you’re interested.
> what criteria do a set of notes have to have to be considered a key?
Generally, if a set of notes form a major or minor scale, then the music written using those notes is said to be in a major or minor key respectively. However, this is only part of the picture, because you may notice that there are major and minor keys that contain the same selection of notes (like C major and A minor, for example). The other part is based on the tonal center: whether or not a song is in the key of C major or A minor depends on whether C or A “feels like home”.
There are a couple parts to this question, and there are both historical and mathematical reasons that keys are as they are today.
>do they always have to sound good together?
If you played all the notes in the key of C major at the same time, it wouldn’t sound good, but I think you mean “do the notes in the keys always have to work well together.” The answer is yes, because every major key is built using the same blueprint as every other major key. D major contains the same gaps between notes as F major or Bb major or E major, but it just starts on a different note. Similarly, every minor key is built using the same blueprint as every other minor key.
>who created these keys
I’m no expert on music history, so my understanding is limited in this regard, but I believe the major scale and its modes were established as organizations of pitches to be used in Gregorian chant music in the Middle Ages. Now, the more interesting question is “how did we decide on that collection of pitches” and that leads into the more mathematical side of music, which I can elaborate on if you’re interested.
> what criteria do a set of notes have to have to be considered a key?
Generally, if a set of notes form a major or minor scale, then the music written using those notes is said to be in a major or minor key respectively. However, this is only part of the picture, because you may notice that there are major and minor keys that contain the same selection of notes (like C major and A minor, for example). The other part is based on the tonal center: whether or not a song is in the key of C major or A minor depends on whether C or A “feels like home”.
There’s a “devil’s interval” between the 4th and the 7th (in the key of C these are F and B) which don’t sound very pleasing. But “suspense” is just as important as “light” in music, so “sound good together” depends on the context. Check out the opening riff
[https://www.youtube.com/watch?v=0lVdMbUx1_k](https://www.youtube.com/watch?v=0lVdMbUx1_k)
There’s a pattern for working out a major key, in terms of *tones* and *semitones,* which goes:
T T S T T T S
A *tone* is 2 frets on a guitar or 2 adjacent keys on a piano, and a *semitone* is one fret or key. So if we want to know the notes in the key of C major, we start on the C and follow the pattern.
The other common key is *minor*, and the pattern for that is T S T T S T T
|Note|Major|Minor|
|:-|:-|:-|
|C|1st (root)|1st (root)|
|C# / Db|||
|D|2nd|2nd|
|D# / Eb||3rd|
|E|3rd||
|F|4th|4th|
|F# / Gb|||
|G|5th|5th|
|G# / Ab||6th|
|A|6th||
|A# / Bb||7th|
|B|7th||
If you work out the notes in A minor, you’ll see that they, like C major, are all white notes. The ancient Greeks had a “mode” using “all white notes” for every starting note:
C Ionian (what we call the Major key)
D Dorian
E Phrygian
F Lydian
G Mixolydian
A Aeolian (our minor key)
B Locrian
===
So we’ve defined an octave, split it into 11, and used 7 of those in a scale. We also know that the 4 and the 7 are , well, a bit dodgy, so we leave those out and just have 5, or pentatonic, scale, and that seems to be hardwired into us:
There’s a “devil’s interval” between the 4th and the 7th (in the key of C these are F and B) which don’t sound very pleasing. But “suspense” is just as important as “light” in music, so “sound good together” depends on the context. Check out the opening riff
[https://www.youtube.com/watch?v=0lVdMbUx1_k](https://www.youtube.com/watch?v=0lVdMbUx1_k)
There’s a pattern for working out a major key, in terms of *tones* and *semitones,* which goes:
T T S T T T S
A *tone* is 2 frets on a guitar or 2 adjacent keys on a piano, and a *semitone* is one fret or key. So if we want to know the notes in the key of C major, we start on the C and follow the pattern.
The other common key is *minor*, and the pattern for that is T S T T S T T
|Note|Major|Minor|
|:-|:-|:-|
|C|1st (root)|1st (root)|
|C# / Db|||
|D|2nd|2nd|
|D# / Eb||3rd|
|E|3rd||
|F|4th|4th|
|F# / Gb|||
|G|5th|5th|
|G# / Ab||6th|
|A|6th||
|A# / Bb||7th|
|B|7th||
If you work out the notes in A minor, you’ll see that they, like C major, are all white notes. The ancient Greeks had a “mode” using “all white notes” for every starting note:
C Ionian (what we call the Major key)
D Dorian
E Phrygian
F Lydian
G Mixolydian
A Aeolian (our minor key)
B Locrian
===
So we’ve defined an octave, split it into 11, and used 7 of those in a scale. We also know that the 4 and the 7 are , well, a bit dodgy, so we leave those out and just have 5, or pentatonic, scale, and that seems to be hardwired into us:
There’s a “devil’s interval” between the 4th and the 7th (in the key of C these are F and B) which don’t sound very pleasing. But “suspense” is just as important as “light” in music, so “sound good together” depends on the context. Check out the opening riff
[https://www.youtube.com/watch?v=0lVdMbUx1_k](https://www.youtube.com/watch?v=0lVdMbUx1_k)
There’s a pattern for working out a major key, in terms of *tones* and *semitones,* which goes:
T T S T T T S
A *tone* is 2 frets on a guitar or 2 adjacent keys on a piano, and a *semitone* is one fret or key. So if we want to know the notes in the key of C major, we start on the C and follow the pattern.
The other common key is *minor*, and the pattern for that is T S T T S T T
|Note|Major|Minor|
|:-|:-|:-|
|C|1st (root)|1st (root)|
|C# / Db|||
|D|2nd|2nd|
|D# / Eb||3rd|
|E|3rd||
|F|4th|4th|
|F# / Gb|||
|G|5th|5th|
|G# / Ab||6th|
|A|6th||
|A# / Bb||7th|
|B|7th||
If you work out the notes in A minor, you’ll see that they, like C major, are all white notes. The ancient Greeks had a “mode” using “all white notes” for every starting note:
C Ionian (what we call the Major key)
D Dorian
E Phrygian
F Lydian
G Mixolydian
A Aeolian (our minor key)
B Locrian
===
So we’ve defined an octave, split it into 11, and used 7 of those in a scale. We also know that the 4 and the 7 are , well, a bit dodgy, so we leave those out and just have 5, or pentatonic, scale, and that seems to be hardwired into us:
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