Theory & harmony
Tonic and dominant
The tonic is the home note and chord of a key, and the dominant is the chord built on the fifth degree above it, the tension between them drives most Western tonal music.
In C major the tonic is C and the dominant is G. The dominant contains the leading note, B, which pulls upward to the tonic, and that pull is the engine of tonal harmony: the dominant creates the expectation that the tonic satisfies. Add a seventh to the dominant and the pull strengthens further.
Recognising the pair by ear is the single most useful ear-training skill for an orchestral player, because it tells you where a phrase is heading before you get there, which in turn tells you how to shape it and where the intonation has to be exact.
The subdominant, built on the fourth degree, is the third member of the primary group, and the progression tonic–subdominant–dominant–tonic underlies an enormous amount of repertoire from Bach to pop.
Related terms
Every term in this glossary is taught in context somewhere in Arco's curricula, on the staff, on the keyboard, and on your own fingerboard at the same time.