Both C major and G mixolydian have the same constituent notes, so how can I tell whether a piece is in one or the other?

  • Identifying the home tone is always a good help. You recognize it when you listen to the tune and check the final chord or the closing passage. – Albrecht Hügli Jun 18 '20 at 14:51
  • Hi axelotl, this is a question that gets asked a lot on this site so I've closed it as a duplicate. There are more questions out there that go over this so I'll add them to the duplicate list when I find them. – Dom Jun 18 '20 at 15:00

The whole point of recognising a set of notes that could belong to seven different modes is where 'home' is perceived.

Home is where the piece feels at rest, like it coud be finished at that point. It's much easier to establish that in key C (C Ionian), because often the final cadence is perfect, which involves V>I (G>C). Since the B note (leading note) from C major is the one semitone away from the root, it just feels right.That works for single notes, and also, probably more convincingly, for chords (triads will do).

For a piece in G Mixolydian, though, there's no leading note - the seventh note in that scheme is a tone away from the root. However, if there's a bit of a blues feel to the piece - due to m7 being present - that's a pointer. And if the piece keeps coming back to G (as a note or chord), then that's another pointer.

  • Hi Tim, thank you for your answer. To clarify, then the perception of "home" is created by the frequency of the occurrence of a note and the chords leading to that note? This I think is the point which confuses me most about keys - how this idea of "home" is established. – axelotl Jun 18 '20 at 14:38

If you feel that the 'home note' is C, then it's C major (or maybe C Ionian!)

If you feel that the 'home note' is G, then it's G mixolydian.

Maybe you can't hear a clear home note? In that case, the piece may simply not have a single clear 'key' or 'mode'. The key or mode of a piece is not always an absolute, objective fact. It's more like a perspective from which the piece may be analyzed.

  • It may be that in an exam there’s show an ambiguous passage of the middle a melody and what they want to hear is arguments for one or the other solution... – Albrecht Hügli Jun 19 '20 at 4:26

In C major the root tone is C the dominant is G The melody ends on the root tone or eventually on a chord note of C.

In G mixolydian the root tone is G. You will also find a kind of “dominant” tone, it’s called the tenor or repercussio (also named repetitio as it is mor often repeated) in Gregorian chant: this is the 5th (D). The final tone is G and so there is no leading tone as we have F-G (= minor7 = 2 semitones below the root tone.

This tenor tone has nothing to do with the Tenor Part (SATB).

  • Hi Albrecht, thanks for your answer. Does this mean that in non-western music, it doesn't have meaning to talk about keys? A lot of traditional bagpipe music, for instance, doesn't finish on the tonic (e.g. some versions of the Skye Boat Song) – axelotl Jun 18 '20 at 14:40
  • These are probably modes. I think you know the modes as you ask about mixolydian. If not you have to look up the modes. It can be that also in non western music you find modal tunes (in other keys), maybe depending of the tuning of the instrument. So if you have to define a mode you still need minding the key (signatur, not scale or tonality). – Albrecht Hügli Jun 18 '20 at 14:50
  • @axelotl - Skye may not finish on the root note, but the root chord is still there. – Tim Jun 18 '20 at 15:07

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