Since college, I have been confused about musical modes. Not because it was so difficult to understand but mainly because it wasn't explained correctly and clearly. I think when a professor keeps repeating over and over again that "musical modes are very difficult to understand," one might think that the teacher was oblivious about the subject or didn't have a clue how to explain in layman's terms. So, now after 3 years, I finally realized that these modes are not that difficult to understand.
Okay, there are seven different musical modes: Ionian mode (starts on the tonic), Dorian Mode (starts on the supertonic), phrygian mode (starts on the mediant), lydian mode (starts on the subdominant), Mixolydian mode ( starts on the dominant), aeolian mode (starts on the submediant) and Locrian mode (starts on the leading tone).
I'm going to explain one mode which is the Dorian mode. This mode starts on the supertonic.
Remember this key: to recognize a mode of any scale, you will need to first recognize which note (scale degree) the mode starts and ends on.
Let's use the C Major scale which is the easiest scale. The C Major scale doesn't have any accidentals (no flats and no sharps).
If you have a piano keyboard, you can look at all of your white keys starting with Middle C and say the names of all the notes in the C Major scale aloud: C-D-E-F-G-A-B-C.
These seven notes are also scale degrees. A scale degree is a name for a particular note that is related to the tonic. C is the tonic (first scale degree).
Now, focus your attention on D. Why focus on D? D is the second note (supertonic) in the C Major scale. When you start on the second note (supertonic) of a specific scale, this is called the Dorian mode.
Since we are dealing with C Major scale, the Dorian mode is the mode that starts and ends on the second note degree (supertonic (D)) of C Major scale. Now, we are going to write out the D Dorian scale. The D is now the tonic because it is the first note in the Dorian mode.
This is the order of the Dorian mode starting on D: D (the tonic), E ( supertonic), F ( mediant,), G (subdominant), A (dominant), B (submediant), C, (leading tone) and then back to the tonic D.
How to find modes in a musical piece:
Number 1: Recognize what note the piece begins and ends on. However, a musical piece doesn't always end or return to the tonic.
Number 2: Remember your key signatures. The best way to remember key signatures is by remembering the "Circle of Fifths."
Number 3: Check the key signature. Now, lets say a piece starts on D and ends on D but we don't know if it's a D Dorian, a D Major or a D minor. Now to recognize a D Dorian mode, you have to think about C Major scale. The C Major scale doesn't have any accidentals. So if you check the key signature and there are no accidentals, this is a big indication that this piece is not in D Major or in D minor. D Major has accidentals and D minor has accidentals. D minor's leading tone is C#. So, the piece is not in D minor. So the answer is D Dorian.
These music modes applies to other music scales. You can find them on the "Circle of Fifths."