The submediant is the sixth scale degree of a major or minor scale, and the triad built on it (vi in major, VI in minor) functions in AP Music Theory as a tonic substitute, a weaker predominant, and the typical resolution chord in a deceptive progression (V to vi).
The submediant is scale degree 6, sitting a third below the tonic (that's where the "sub" comes from, just like the mediant sits a third above). In C major, the submediant is A; in A minor, it's F. Per the CED (PIT-1.E.1), you need to identify it by name and number in both performed and notated music, right alongside tonic, supertonic, mediant, subdominant, dominant, and leading tone.
The chord built on it is where things get interesting. In a major key it's the minor triad vi; in a minor key it's the major triad VI. The CED gives it two jobs (PIT-2.J.1). First, it's a tonic substitute, since vi shares two notes with I and can stand in for it to keep a phrase moving. Second, it's a weaker predominant, often leading to ii or IV on the way to V. Its most famous gig is the deceptive progression (PIT-2.J.2), where V resolves to vi instead of I. Your ear expects home, and the submediant is the bait-and-switch.
The submediant shows up in two different units, which is exactly why it's worth knowing cold. In Unit 1 (Topic 1.4, learning objective 1.4.B), it's vocabulary. You hear or see a pitch and name its function relative to tonic. In Unit 5 (Topic 5.2, learning objective 5.2.A), it becomes harmony. You have to identify and describe what the vi (VI) chord is doing in a progression, in both performed and notated music. The deceptive progression is one of the few progressions the CED calls out by name as "distinctive enough in sound and/or context" to get its own label, and the submediant is the star of it. If you can hear V going somewhere that isn't I, you can usually bet it went to vi.
Keep studying AP Music Theory Unit 5
Visual cheatsheet
view galleryDominant (Units 1 & 5)
The dominant sets up the submediant's signature move. In a deceptive progression, V resolves to vi instead of I, so the submediant only sounds "deceptive" because the dominant promised tonic first. You can't analyze one without the other.
Tonic (Unit 1)
The vi chord shares two of its three notes with the tonic triad, which is why it works as a tonic substitute. Think of vi as tonic wearing a disguise, close enough to feel stable but different enough to keep the phrase going.
Chord Progression (Unit 5)
The submediant is a workhorse in standard progressions. The vi to ii or vi to IV move is its weaker-predominant role, pushing harmony toward V. Recognizing where vi sits in the functional chain (tonic, predominant, dominant) is the whole point of Unit 5 analysis.
Scale Degree (Unit 1)
Submediant is one of the eight scale degree names in PIT-1.E.1. Its name is a mirror trick. The mediant sits a third above tonic, so the submediant sits a third below. Knowing that logic makes the whole naming system easier to memorize.
Expect the submediant in two flavors of question. In Unit 1 material, you'll name scale degrees from notation or by ear, so given a key and a pitch, you label it "submediant" or scale degree 6. In Unit 5 material, multiple-choice and analysis questions ask what the vi (VI) chord is doing in context. Practice questions push exactly this distinction, like how vi functioning as a tonic expansion differs from vi arriving via a deceptive cadence. Aural questions love the deceptive progression because it's one of the most recognizable sounds in the course (V resolves, but not home). In Roman numeral analysis FRQs and part-writing, you may need to spell vi correctly, label a V to vi motion as deceptive, and voice-lead it without parallels. No released FRQ hinges on the word "submediant" itself, but the vi chord shows up constantly in harmonic dictation and figured bass realization.
Both names start with "sub," but they point at different degrees. The subdominant is scale degree 4 (a fifth below tonic, mirroring the dominant a fifth above), while the submediant is scale degree 6 (a third below tonic, mirroring the mediant a third above). Functionally they overlap a little, since both can act as predominants, but IV is the stronger predominant and vi is the weaker one that also doubles as a tonic substitute.
The submediant is scale degree 6, located a third below the tonic, and it's A in C major and F in A minor.
The submediant triad is minor (vi) in a major key and major (VI) in a minor key.
Per the CED, the vi (VI) chord functions either as a tonic substitute or as a weaker predominant chord leading toward V.
In a deceptive progression, the dominant chord resolves to the submediant instead of the tonic, and that V to vi sound is one the exam expects you to recognize by ear.
Don't mix up submediant (degree 6, third below tonic) with subdominant (degree 4, fifth below tonic).
Submediant as tonic expansion and submediant as deceptive resolution are different functions, and context decides which label fits.
The submediant is the sixth scale degree of a major or minor scale, sitting a third below the tonic. The chord built on it is vi in major keys and VI in minor keys, and it can act as a tonic substitute or a weaker predominant.
No. The subdominant is scale degree 4 (a fifth below tonic) and the submediant is scale degree 6 (a third below tonic). They're both "sub" because they mirror the dominant and mediant below the tonic, but they're different degrees with different chord functions.
A deceptive progression happens when the dominant chord (V) resolves to something other than tonic, most often the submediant (vi). Your ear expects I, gets vi instead, and that surprise is exactly what AP aural questions test.
No. The CED gives vi two distinct functions. It can be a weaker predominant moving toward ii, IV, or V, or it can substitute for the tonic since it shares two notes with the I chord. You have to read the surrounding chords to know which job it's doing.
In C major, the submediant is A, and the vi chord is A-C-E (an A minor triad). In A minor, the submediant is F, and the VI chord is F-A-C (an F major triad).
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