The two main categories of musical modulation are diatonic and chromatic modulation. In diatonic modulation, the transitional device (chord or pitch) used to modulate is diatonic to both the old and new key. In chromatic modulation the transitional device (chord or pitch) used to modulate is chromatic to the old key and leads to the new key. Since both chords and pitches can be used as transitional devices, there are two types of diatonic modulation called common (or pivot) chord and common tone modulation. There is also another type of modulation called enharmonic modulation which involves the enharmonic respelling of pitches. This type of modulation can be categorized as either diatonic or chromatic depending on how we view the respelled pitch. I will cover this and chromatic modulation in more detail next week.
This Learning Music With Ray video discusses musical modulation. In it, I explain the meaning and aspects of modulation as they relate to harmonic structure and key center. I list the various types of modulation found in music. I then discuss two types of modulation in detail, providing musical examples throughout the discussion.