Real cases
A case · you decide
Root and the one bass note
Root — the hum-the-bass ear in a high-school band's practice room
The band's pianist is out sick. The guitarist hums a single low C under the chorus melody and asks what chord goes there.
A C in the bass does not decide the chord on its own. It is the root of C major (C–E–G), the third of A minor (A–C–E), and the fifth of F major (F–A–C).
The melody note above it is an E. That rules F major out, because F major has no E in it.
What should the band try first over the C bass with an E in the melody?
The band votes for A minor. It changes the whole chorus from triumphant to wistful, and it came from asking what else that one bass note could be.
A case · you decide
Pull and Bridge: where the verse lands
Pull & Bridge — a cadence ear working with a songwriting coach
The verse is written. It ends on the home chord, and the band keeps stopping dead before the chorus as if the song were over.
Ending V to I is an authentic cadence. It sounds like a full stop, which is why the band keeps pausing.
Bridge, the coach, never writes the fix. It only asks what the verse is supposed to do: finish, or lead somewhere.
The verse needs to throw the listener into the chorus. How should it end?
With the verse ending on V, the chorus lands like an answer. The fix was one chord, and the band found it by naming what the ending was doing.
A case · you decide
Root and Cycle: four chords in one bass line
Cycle & Root — a 17-year-old learning the chords to a song everyone at school is covering
Nika hums the bass of the chorus into the app: C, then G, then A, then F, and round again. Root hears each note; Cycle hears the shape they make together.
In a major key, each scale note is the root of a chord with its own Roman numeral. Root names what each bass note could be; Cycle asks what the four of them are when you hear them as one loop.
Most pop choruses sit on a small set of loops. Recognising the loop is faster than working out each chord from scratch.
The bass runs C – G – A – F. Which progression is Nika most likely hearing?
A bass line is a map. Root reads each point on it; Cycle reads the route.