There are many benefits to having a good ear. People born with a good ear are often described as "naturals" when it comes to music ability. Ear training will improve your ability to hear and transcribe what others are playing as well as help you with writing or improvising music. The idea is to get what's in your head, out.
1. Know what the different intervals sound like and be able to name them.
2. Be able to sing the different combinations of intervals.
A good way to start your ear training is to sing the first four notes from select modes. There are seven modes in total, but all seven can be constructed from making alterations to these four.
Check out the notes below, which all start on C and are grouped in stacks.
1. The first is C Major, C-D-E-F
2. The second group is C Minor, C-D-Eb-F
3. The third is C Phrygian, C-Db-E-F
4. The fourth is C Lydian, C-D-E-F#
Study this graphic, look at it when singing along with the exercise, and know that those are the sizes of the intervals you will sing. You have movement of half steps-1 fret on the guitar, and movement of whole steps-2 frets on the guitar. All of the basic seven modes are a combination of half and whole steps. Exotic scales half many interesting, and sometimes intimidating names, but know that most of them can be constructed by altering the basic seven modes with raised, lowered or added chromatic notes. This lesson is meant to train your ear, so don't feel like you have to understand all the theory to benefit from it.