The recipe — what makes a dominant 7th
Before we colour it, alter it or resolve it, we have to build it. A dominant 7th is four notes stacked in thirds — and there are three ways to see it. Two of them we'll learn right now; the third (a tritone pair) has a chapter of its own later. The more ways you can hold a chord in your mind, the faster you'll find it under your hands.
Take a plain major triad (1 · 3 · 5) and drop one more third on top — a minor 7th above the root, the ♭7. That's it. On A: the A-major triad A · C♯ · E, plus G — A7.
Quick way to find that ♭7: it's “octave minus 2” — two semitones below the root's octave. From A up to the next A, come down two — that's G.
The major 3rd makes it bright; the ♭7 makes it lean. Together they are the tension the whole lesson is built on.
Skip the root and look up a major 3rd: the notes 3 · 5 · ♭7 form a diminished triad. So A7 is a C♯ diminished triad (C♯ · E · G) sitting over an A in the bass.
This is one useful pianist’s grip: root down low, the diminished triad up top. It leads naturally into the fuller voicings later.
Raise that ♭7 by a half-step and you get a major 7th (A · C♯ · E · G♯ = Amaj7). The symbols describe different chord qualities: major 7 uses a major triad plus a major seventh; dominant 7 uses a major triad plus a minor seventh. What either chord does depends on the music around it.
Chord quality is what it is; function is what it does
“Dominant seventh” names a sound: 1 · 3 · 5 · ♭7. “Dominant function” names a job: creating motion toward a destination. The same chord quality can do several jobs.
Resolve home
G7 → C. Here G7 is V7: dominant quality and dominant function agree.
Point somewhere temporary
A7 → Dm in C major. A7 is V7/ii, a secondary dominant that briefly makes D feel like home.
Be the home sound
C7 can be the tonic in a C blues. Its quality is dominant; its function is tonic.
Three bits of symbol literacy that prevent years of confusion
“7” means dominant quality
C7 means C–E–G–B♭. Compare Cmaj7 (B natural) and Cm7 (E♭ and B♭). A bare 7 after a major letter name implies the major triad plus ♭7.
Extensions include the seventh
C9 is a dominant seventh with a 9th; C13 is a dominant seventh with a 13th. Pianists commonly omit the 5th, and usually omit the natural 11th because it rubs against the 3rd.
Minor keys still need a major V
In D minor, A7 uses C♯, the raised 7th of D, to pull into D. That note comes from harmonic or melodic minor. The destination is minor; the functional V chord still has a major 3rd.
Build a dominant — one third at a time
Pick any root and watch the chord assemble: the major triad first, then the ♭7 that turns it dominant. The keyboard shows where your hands go; press play to hear each step.
The 3rd and the ♭7 you just stacked sit a tritone apart. They are the ordinary dominant’s guide tones. Extensions and alterations preserve that pair; suspended dominants deliberately replace the 3rd with a 4th.
Try this exercise away from the keys: sing the major triad (1 – 3 – 5), then reach up and add the ♭7 on top. “B major… plus A.” Then move the added note into different octaves and inversions — you'll hear the same dominant colour in four shapes. Training your ear to hear “triad + ♭7” is how you'll recognise a dominant 7th anywhere.
Play it yourself — connect your keyboard
Got a MIDI keyboard plugged in? Connect it and the site will analyse common triads, seventh chords and the dominant colours taught here while lighting the notes. Some pitch sets have more than one valid name, so the readout may show both. (Works in Chrome/Edge; no keyboard needed to read the rest of the lesson.)
Play A · C♯ · E — it says “A”. Add G on top — now it says “A7”. Slide that G up to G♯ — “Amaj7”. Flatten the 9 (add B♭) — “A7♭9”. Watch the name change as you build every chord from the lesson by hand.
The dominant 7th and its tritone
A dominant 7th is 1 · 3 · 5 · ♭7 — on A, that’s A C♯ E G. Inside it, the 3rd (C♯) and the ♭7 (G) sit a tritone apart. That single restless interval is the whole reason this chord exists: it leans, and it wants to fall home.
Those two notes — the 3rd and the ♭7 — are the guide tones of an ordinary dominant. They carry its clearest pull. Suspended dominants are the useful exception: they replace the 3rd with a 4th, then often resolve that suspension back to the 3rd.
Most colours in this lesson preserve those guide tones; the suspended family is the deliberate exception that replaces the 3rd.
Throughout, the chords are written on a grand staff: the left hand holds the foundation (root + ♭7) on the bass clef, the right hand plays the colour up top. That split is not decoration — it’s how these chords are actually played. More on the method in the voicing chapter.
Natural extensions — the 9th and 13th
Before we alter anything, we can simply make the chord taller by stacking more thirds: add the 9th, then the 13th. These are consonant, singing colours — the everyday sound of funk, soul and gospel.
Suspended dominants — 7sus4 & 9sus4
Push the 3rd up one step to the 4th and the chord goes weightless — the leading tone is suspended, waiting. The 9sus4 (the “gospel sus”) adds a 9th for that creamy, quartal neo-soul sound.
A 7sus4 usually falls to a plain 7 (the 4th drops to the 3rd) before resolving — a suspension inside the dominant. We’ll hear it land in the resolution chapter.
Altered 5th — 7♭5 & 7♯5
The 5th is the most expendable note in the chord, so it’s the first we bend. Lower it (7♭5, whole-tone and weightless) or raise it (7♯5, augmented and lifting).
Altered 9th — 7♭9 & 7♯9
Now knock the 9th out of tune. The ♭9 is dark and dramatic — a diminished chord lives inside it. The ♯9 rubs the major 3rd against a sharp 9th (≈♭3): the gritty “Hendrix” colour.
A7♯9’s top note is written B♯ (a raised ninth), not C — same key, correct name. And hidden in A7♭9 is a C♯ diminished 7th: the 3-5-♭7-♭9 stack is a diminished chord. That’s its secret.
The ♯11 and the ♭13
Two more colours, often misunderstood. The 7♯11 (the Lydian dominant) keeps its natural 5th and floats a ♯11 above for a clear, spacious sound. The 7♭13 lowers the 13th for a darker altered weight.
7♭5 vs 7♯11: a ♭5 replaces the 5th; a ♯11 adds to it (both 5 and ♯11 present). 7♯5 vs 7♭13: the same sounding piano pitch can have two spellings, but ♯5 replaces the 5th while ♭13 can coexist with it. Spelling tells you the note’s role in the chord.
Fully altered — the combinations & “7alt”
Combine an altered 5th with an altered 9th and you get the four classic altered dominants. Take all the alterations together and you get 7alt — the altered scale’s chord, and a common jazz V choice before a minor chord.
That’s the whole family. Below, you can summon and hear every one of the sixteen — and the next section explains exactly how each voicing was built.
The Dominant Explorer
Pick a root and any of the sixteen chords. The grand staff shows a practical two-hand voicing, the keyboard splits it into hands, and where a shortcut exists, the upper-structure triad appears.
How the Explorer voicings are built
A complete theoretical stack and a practical piano voicing serve different purposes. These examples use one clear, contemporary approach; treat the rules below as a reliable starting point, then adapt them to the melody, register, hand span and ensemble.
- Prioritise the guide tones. The 3rd and ♭7 identify an ordinary dominant; a sus chord deliberately replaces the 3rd with the 4th.
- Start with a shell. Root + 3rd + ♭7, root + ♭7, or the rootless 3rd + ♭7 pair can all work.
- Add colour where it speaks clearly. Avoid doubling the ♭7 in these examples because it is already present below; other musical contexts may call for it.
- Drop the natural 5th whenever an altered 5th or ♭13 takes its place. The 5th is the first thing to go.
- Spice on top. Put the alterations where they ring clearly, above middle C.
- Open at the bottom, close at the top. Low close intervals often blur on piano, so widen or roll them when needed.
Hold the 3rd and ♭7 as the dominant shell, then place a familiar triad above it. The upper structure supplies colour; the shell supplies the chord identity:
- B♭ minor / A → A7♯5♭9
- E♭ major / A → A7♭5♭9
- C minor / A → A7♭5♯9
- B major / A → A7♯11
- C♯ dim7 over A → A7♭9
Two suspended colours worth memorising, both built a whole tone below the root:
- Major triad, a whole tone down → A9sus4(no5) (often written A11 in shorthand).
- Major-7th chord, a whole tone down → A13sus4. Gmaj7/A contains D, the suspended 4th, and no C♯ major 3rd.
Add or resolve the C♯ when you want the sound to become an ordinary A13.
Rootless voicings — when the bass is taken
Everything so far keeps the root in your left hand. But play with a bassist — or walk your own bass — and the root is already covered. Jazz pianists drop it and keep only what matters: the guide tones plus the colour. Four notes, one hand.
There are two classic shapes, named for which guide tone sits at the bottom:
- A-form — built from the 3rd: 3 · 5 · ♭7 · 9. The 3rd anchors the bottom.
- B-form — built from the ♭7: ♭7 · 9 · 3 · 13. The ♭7 anchors the bottom.
- To alter, swap in place: the 5 becomes ♯5/♭13, the 9 becomes ♭9/♯9, the 13 becomes ♭13. The shape barely moves.
These sit in one hand around middle C — which frees the other hand to play the melody, add colour or support a solo. They are common jazz ii–V voicings.
With no root, the voicing’s dominant quality rides on the guide tones — the same tritone we stacked when we first built the chord. The bass player, melody and resolution tell the listener which root that shared tritone belongs to.
Inversions and shells — four basses, several useful grips
Inversion is decided by the lowest note. Voicing describes how every note is arranged above it. Choose a root below: the four cards keep the same chord quality while moving a different chord tone into the bass.
Solo piano may need a root and fuller colour. With a bassist, the rootless 3rd–♭7 pair can be enough. A two-note root–♭7 grip is an incomplete shell: useful, but it needs the harmony or another player to supply the missing 3rd.
Why a dominant resolves
Remember the tritone — the 3rd and ♭7 leaning on each other? Resolution is simply letting that tension collapse. The dominant falls a fifth (counter-clockwise on the circle) and its guide tones step into the new chord.
The motion is beautifully economical. From A7 to D:
- The 3rd → the root: C♯ rises a semitone to D (the leading tone doing its job).
- The ♭7 → the 3rd: G falls to F♯ (major) or F (minor).
- Any ♭9 → the 5th: B♭ drops to A.
Two voices barely move, and the whole world changes. That is voice leading.
A dominant can land on a major or a minor chord. In gospel especially, altered dominants love to resolve to a minor — A7alt → D minor. Hear both in the Lab below.
Don't just play it — sing it. The dominant’s ♭7 falls to the home chord’s 3rd: a half-step into major, a whole step into minor. Then sing the dominant 3rd rising a half-step to the tonic. Train your ear to hear the cadence, not the lone chord.
The Resolution Lab
Choose a dominant, choose its home, and watch the guide tones move. Then press play and feel the lean-and-land.
Six ways a dominant can move
The home cadence. A7 → D (or Dm). The strongest resolution there is.
E♭7 → D. E♭7 shares A7’s exact tritone (G + C♯), so it pulls to the same home — now with a smooth ♭2→1 bass. The secret behind countless jazz turnarounds.
A7 → B♭ (or Bm). The ear expects D; you give it a neighbour instead. Surprise and delay.
C7 → D. A dominant a whole step below the target (♭VII7) sneaks in through the back door — a gospel and Steely-Dan favourite.
A7sus4 → A7 → D. Delay the 3rd with a 4th, let it fall, then resolve. Tension stacked on tension.
B♭7 → A7 (or up: A♭7 → A7). Approach a dominant from the dominant a semitone above or below and just slide — the whole chord shifts in parallel. It's the engine of Jailhouse Rock, and a spicy way to arrive.
Strings of dominants round the circle — E7→A7→D7→G — are how whole tunes travel. Each is a V pulling to the next.
Line clichés — the dominant that sneaks in
Dominants don't only announce themselves at cadences. Very often one appears for a single beat — created by a voice quietly moving by half-steps while the chord underneath barely changes. You've heard these a thousand times without naming them.
Hold a C chord and walk the top voice down chromatically:
C → Cmaj7 → C7 → F
The top note falls C → B → B♭, and on that B♭ the chord momentarily becomes a C7 — a secret dominant that then pulls to F. That's the guitar figure in the Beatles' “Something.”
Walk a bass line up and a passing chord can become a dominant of the next:
C → A7/C♯ → Dm → …
That A7 in the middle is a secondary dominant (V7/ii). Its C♯ bass connects C to D by semitone while the chord nudges the ear toward D minor.
In Dorian (a minor scale with a natural 6th), the IV chord turns into a dominant 7th. Vamp i m7 → IV7 (say E♭m7 → A♭7) and you get an open-ended funk groove: dominant quality used as modal colour rather than as V7 of a new home.
The circle of fifths — every road home
All that motion has a map. On the circle of fifths, an authentic dominant-to-tonic resolution is one step counter-clockwise. Other routes — tritone substitution, backdoor motion, deceptive resolution and longer chains — make different shapes around the same tonal map. Pick a home key and a method; watch the road light up, then hear it resolve.
A counter-clockwise step shows the perfect-fifth fall of V→I and secondary-dominant chains. A ♭II tritone substitute approaches the tonic by semitone instead; it works because it carries the original V7’s guide-tone tritone. The map lets you compare those routes without pretending they move in the same way.
Tritone substitution — two dominants, one tritone
Here is the third way to think about a dominant 7th — and a composer’s favourite trick. The core pull of an ordinary dominant is its tritone (the 3rd + ♭7). Two dominant roots a tritone apart share the same two guide-tone pitches with their roles reversed, so one can substitute for the other when the voice leading fits. Keep those pitches and swap the bass to get two dominants for the price of one.
Put the two guide tones (3 and ♭7) in your right hand and leave them there. In the left hand, alternate the root + 5th of each partner — B & F♯, then F & C. Same right hand, two basses, two dominants. That muscle memory is the whole trick.
Tension & release — using the dial
Alterations change the colour and available voice leading of a dominant. This five-step comparison is a practical listening path, not a universal ranking: melody, register, rhythm, duration and voicing can make any version feel more or less tense.
Three practical questions help you spend tension:
- Tension lives on the V. Spend it at the end of the phrase, right before the release — not scattered everywhere. One dark dominant lands harder than four mild ones.
- Match the colour to melody and destination. Altered sounds are common before minor, but they can resolve beautifully to major too. Check every tension against the melody note.
- Delay multiplies tension. Hold a sus first, stack the ii in front, or sneak in the tritone sub — the longer the ear waits, the bigger the release.
7 — plain lean → 9 — warm lean → 13 — lush lean → 7♭9 — dark pull → 7alt — dense altered grip. These are five contrasting colours over the same tritone engine, ordered here as an ear-training path rather than an objective tension scale.
Not “can you play a 7♭9” — but choosing the right lean for the moment: gospel reaching for a minor vi wants the dark ♭9; a pop chorus heading to a bright I wants a clean 9; a ballad’s last cadence earns the full alt. Turn the dial with intention, and resolution stops being theory and becomes phrasing.
Scale colours — what to play over each dominant
Chord-scale choices are practical note collections for melody and improvisation. Start with the chord tones, account for the melody and destination, then choose a scale whose remaining notes give the colour you want. These seven are common choices, not the only possible answers.
For an ordinary dominant, make sure the collection supports the root, major 3rd and ♭7; for a suspended dominant, support the 4th in place of the 3rd. Then check every added note against the chord symbol and melody.
Several colours come from melodic or harmonic minor: Lydian dominant is mode 4 of melodic minor, Mixolydian ♭13 mode 5, altered mode 7, and Phrygian dominant mode 5 of harmonic minor. Mixolydian itself comes from the major scale; half–whole diminished and whole-tone are symmetrical scales.
Choose a scale that contains the chord tones and the colour you need. Mixolydian is a common start for a plain dominant; Lydian dominant supports ♯11; half–whole diminished supports ♭9 with natural 13; Phrygian dominant supports ♭9 and ♭13 on a V of minor; altered supports the full 7alt collection. The Explorer lets you hear each proposed match, but melody and resolution still decide.
Secondary dominants & diminisheds — borrowed leading tones
So far our dominant was the V of the key. But any chord can be handed its own leading-tone pull — and there are two ways to do it. The secondary dominant (V7/x) borrows that chord’s V7; the secondary diminished (vii°7/x) borrows its leading-tone diminished 7th. And here is the secret that ties the whole lesson together: they are the same chord — a diminished 7th is a 7♭9 with its root removed.
Earlier we found C♯°7 inside A7♭9 (A · C♯ · E · G · B♭ — remove the A). In this context, C♯°7 → Dm and A7♭9 → Dm share the decisive C♯–G tritone and the same target. The symmetrical diminished chord can imply four different dominant roots, so context and resolution tell you which one the ear hears.
| Target chord | Secondary dominant | Secondary diminished | Hear both |
|---|
One borrowed leading tone is a raised eyebrow; a chain of them (E7→A7→D7→G7→C) is a journey home around the circle — the engine of ragtime, gospel turnarounds and jazz standards. Dominants or diminisheds, altered or sus’d or tritone-subbed — all the same wheel, all the same pull.
One diminished, four dominants — the great pivot
Here is the most useful trick a diminished 7th hides. Because it is built of equal minor thirds, it is perfectly symmetrical — it looks the same from all four notes. So a single diminished 7th is the top of four different dominant 7♭9 chords, each a minor 3rd apart, and each pulls home to a different minor key. Slide a bass underneath and choose your destination.
| Bass added | Becomes | Resolves to | Hear |
|---|
Every dominant 7♭9 is a major triad + ♭7 + ♭9 (from the very first chapter) — and its top four notes spell a diminished 7th. Flip which note you call the root and the same diminished shape becomes four different 7♭9 chords, each a minor 3rd apart. And here's the kicker: there are only three unique diminished 7th chords in all of music — learn those three and you own every 7♭9 in every key. The pianist's ultimate shortcut.
This demonstration lands each dominant on a minor home so you can compare one colour consistently. The same 7♭9 chords can also resolve to major. Listen for the root moving down a fifth and for the altered tones finding nearby chord tones; each individual voice chooses its own smooth path.
The blues — where the dominant refuses to resolve
A dominant-seventh quality does not guarantee dominant function. In blues, I7 can feel like home, IV7 can move away from it, and V7 can still drive a cadence. The same four-note quality takes on different jobs.
The 12-bar form in the chosen key — every chord has dominant-seventh quality, while the progression still creates departure, return and turnaround:
Here the I7 isn’t tense — it is the tonic. Funk vamps (one dominant 9th or 13th, forever), soul grooves and modal jazz all live on this idea: the dominant as a stable colour, not a question needing an answer.
Remember the Hendrix chord? Over a blues tonic, the ♯9 is simply the blue note — the minor 3rd sung on top of a major-3rd chord. The 7♯9 is the blues, captured in a single voicing.
Soak your ear in dominant 7ths: B.B. King, Ray Charles, John Mayer and “Stormy Monday” for the blues; Queen, Elton John and Billy Joel for dominants driving pop and rock. The fastest way to own this chord is to keep hearing where it lives.
Ear-training quiz — name what you hear
Reading about a dominant is one thing; hearing it is the goal. Pick a challenge, press play, and name the sound. Your streak is at the top — the notes are chosen at random in a fresh key each time, so you can't memorise the answer, only learn the sound.
Every dominant 7th at a glance — in A
| Chord | Formula | Notes | Two-hand voicing | Scale colour | Character |
|---|
Transpose any of these in the Explorer above. Left hand | right hand shown for the playing voicing.
Practice & assignment
From the plain 7th to the altered — and home
- Run 7 → 9 → 13 then 7♯5 / 7♭5 and 7♭9 / 7♯9 around the circle of fifths, two hands, shell + colour.
- Learn the five upper-structure triads (B♭m, E♭, Cm, B, C♯°) over an A bass — instant altered chords.
- Learn the two rootless shapes on A9 and A13, then alter them in place (9→♭9, 13→♭13) without moving your hand.
- In the Explorer, pick any altered chord, play its scale, then improvise four bars of right-hand melody from that scale over the left-hand shell.
- Take A7alt → D minor through the Resolution Lab, then move it round the circle (D7alt→Gm, G7alt→Cm…).
- On the Circle of Fifths, resolve one home key five ways — authentic, tritone sub, backdoor, deceptive, and a full secondary-dominant chain — and play each.
- In the Tension & Release workbench, hold the phrase and key fixed and turn the dial 7 → 9 → 13 → 7♭9 → 7alt; listen to the same cadence lean harder each step.
- In C major, play each secondary dominant into its target (A7→Dm, B7→Em, C7→F, D7→G7, E7→Am), then chain them home: E7→A7→D7→G7→C.
- Play one ii–V–i in a minor key using a fully-altered V: Em7♭5 → A7alt → Dm.
- Vamp a 12-bar blues in A — every primary chord a dominant 7th — and hear how A7 can feel stable as I7 while D7 and E7 still create departure and turnaround.
Train the sound, not just the shape
- Circle drill (anticlockwise): play any 7th chord, then resolve it to its nearest neighbour anticlockwise — C7→F, A7→D, F7→B♭ — all the way round. Say the target before you play it.
- Sing the two pulls: ♭7 falling to the 3rd (4→3), then the 3rd rising to the tonic (7→1). Sing before you play.
- maj7 vs dom7: have someone play one or the other; name it by ear. One belongs to the key, one leans out of it.
- Guide-tone shell: left hand root+5th, right hand just 3 & ♭7. Run a ii–V–I and let the two guide tones flip 7-3 → 3-7 → 7-3 — only one finger moves.
- The whole-tone trick: over any root, drop a whole step and play a major triad (→ 11th), then a major-7th chord (→ 13th). Gospel and theatric colour in one shape.
- Chromatic slide: approach a target dominant from a semitone above and below (B♭7→A7←A♭7) and feel the parallel shift.
- Line cliché: play C → Cmaj7 → C7 → F, hearing the hidden dominant appear as the top voice falls.
- Blues scale toggle: over a 12-bar blues, wave between the major and minor blues scale of the key — the one chord where both belong.
You now have the core dominant-seventh family, practical rooted and rootless voicings, four inversions, common scale colours and several ways the chord can move. Put one idea at a time into ii–V–I progressions, blues, vamps and songs; musical fluency comes from hearing the job and choosing a sound that fits.
Quick reference
- Dominant quality / function
- Quality describes 1–3–5–♭7; function describes a chord’s job in context. A blues I7 has dominant quality with tonic function.
- Guide tones
- For an ordinary dominant, the 3rd and ♭7 form its defining tritone. A suspended dominant replaces the 3rd with a 4th.
- Shell voicing
- A compact grip that states the harmony: commonly root–3–♭7, root–♭7, or the rootless 3–♭7 pair.
- Upper structure
- A plain triad in the right hand over a foreign bass — instant complex chord.
- Rootless voicing
- Drop the root (a bassist has it); one hand plays 3-5-♭7-9 (A-form) or ♭7-9-3-13 (B-form).
- 7alt
- The altered-scale dominant: ♭9 ♯9 ♯11 ♭13, no natural 5 or 9. A common high-tension V choice before minor or major.
- Dominant 11
- “A11” on a chart = the 9sus4 in practice — the 11 replaces the 3rd.
- Mixolydian
- The plain dominant’s scale: a major scale with a ♭7. Home of 7, 9 and 13.
- Altered scale
- 7th mode of melodic minor: 1 ♭9 ♯9 3 ♯11 ♭13 ♭7 — every alteration at once. The 7alt scale.
- Lydian dominant
- 7♯11 — natural 5 plus a ♯11. A clear, spacious colour; the scale is mode 4 of melodic minor.
- Half-whole diminished
- 8-note scale (half step, whole step, repeating) over 7♭9 — gives ♭9 ♯9 ♯11 and a natural 13.
- Phrygian dominant
- 5th mode of harmonic minor (1 ♭9 3 4 5 ♭13 ♭7) — the V-of-minor scale; Spanish/klezmer colour.
- Whole-tone scale
- Six equal whole steps — the 7♯5/7♭5 dreamscape. No leading tone, pure float.
- Secondary dominant
- The V7 of a chord that isn’t the tonic — V7/ii, V7/V… a borrowed leading moment.
- Secondary diminished
- The vii°7 of a non-tonic chord (C♯°7→Dm). In this context it contains the upper notes of A7♭9 and shares its guide-tone pull.
- Circle of fifths
- The map of keys by fifths; a dominant resolves by stepping one place counter-clockwise.
- Backdoor dominant
- The ♭VII7 a whole step below the target (B♭7→C) — resolves up, a gospel favourite.
- Tension dial
- An ear-training sequence of contrasting colours: 7 → 9 → 13 → 7♭9 → 7alt. Match the colour to the melody and landing.
- Tritone sub
- The ♭II7 that shares the tritone (E♭7 for A7) and resolves to the same home.
- Resolution
- In an authentic V7→I, the root falls a fifth while 3→tonic and ♭7→3rd; if present, ♭9 commonly falls to the 5th.
- Blue note / blues 7th
- In blues, I7, IV7 and V7 all use dominant-seventh quality while serving different functions; the ♯9 sounds like the sung ♭3 above a major 3rd.
- Enharmonic twins
- ♯5 = ♭13, ♭5 = ♯11 by key — but spelled by function.