Four scales (or modes) are commonly used in traditional Irish music:
- Ionian (Major Scale)
- Mixolydian
- Dorian
- Aeolian.
Dorian and Aeolian are both minor scales.
Ionian is more commonly referred to as the Major Scale. This is the most widely used scale in Irish music. It's used in tunes such as “Miss McCloud’s Reel”, “Off to California”, and “The Blackthorn Stick”. The two most popular keys are G and D, with stringed instruments often using A. Sometimes C and F are used.
Examples of mixolydian mode can be found in the tunes “My Love is in America”, “Langstrom’s Pony”, and “Rakish Paddy”.
There is one note different between The Ionian and Mixolydian. The seventh note of the Ionian is flattened by a semitone. A contrasting example of these two modes in use is to be found in the Lennon/McCartney song “With a Little Help From My Friends”. The verse is in the Ionian mode but switches to a mixolydian mode for the chorus.
Dorian mode is the most common form of minor scale in Irish music. Examples of tunes using this mode include “Star of Munster”, “Pigeon on the Gate”, “Green Groves of Erin”, and “Julia Delaney’s”. The majority of “minor” tunes use this mode.
The Aeolian modes is known as the “pure minor”. It is often found in tunes that move to the related major key. “Paddy Lynn’s Delight” and “The Galtee Reel” are examples of this.
You can download PDFs of the Ionian, Mixolydian, Dorian and Aeolian modes.