This question already has an answer here:

What I have been told is V6(over)4 to 5(over)3 means it's really I 6(over)4 to a root position dominant if I wasn't mistaken when taking notes? What is this, what does the 5(over)3 mean, why is this more useful than writing the chords flat out, and what purpose does this (I believe it's a part of the dominant function, so function?) serve?

marked as duplicate by Tim, Richard theory Jun 29 at 14:43

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • 1
    wait I take back it being a function hahaha. It falls into a function according to my notes but it itself being a function is a very dumb thing to say – Frank Badertscher Mar 13 '17 at 0:29

You're talking about what is known as a cadential 6/4 chord, which is a very common embellishment of the V chord. The fifth scale degree is in the bass, but, at first, there's a sixth and a dissonant fourth above the bass which want to resolve to the normal fifth and third respectively (the fourth almost always literally resolves to the third, the sixth sometimes moves differently, like to a seventh above the bass).

You're right that, technically, this harmony has the notes of a I chord in second inversion, and some theorists and textbooks label it as a I6/4. However, most theorists these days prefer for the Roman numerals to indicate the chord's function more than simply its note content. The cadential 6/4 has no functional relationship to a I chord, which is tonic; it has dominant function because actually it's just a dissonant embellishment of the V chord. As such, most textbooks and theorists I know tend to prefer to label it as a V chord in order to show its function.

Whether this is the best possible choice is up for debate, but that's only a symbolism debate. Everyone agrees about the actual function of the chord. Often, composers of the Classical and Romantic periods treated the cadential 6/4 as the primary dissonance in the underlying harmonic structure of their music. For example, the unstable harmony that introduces and (at least theoretically) undergirds cadenzas in concertos is almost always a cadential 6/4. The trill signaling the end of the cadenza tends to mark the resolution of the sixth and the fourth to the fifth and the third above the fifth scale degree in the bass, which then leads to a PAC on I in most cases.

  • so it's a PAC even if there are 2 different chords that fit the dominant function preceded by a subdominant and tonic? – Frank Badertscher Mar 13 '17 at 3:31
  • leading to tonic + soprano landing on the root – Frank Badertscher Mar 13 '17 at 3:32
  • Theorists (and pedants) like inventing names for things. If you think there is a difference in the musical effect of Perfect Cadence and a Perfect Authentic Cadence, then the terms might (or might not) have some meaning for you. But don't forget that the composers who wrote contemporary music in this style (Haydn, Mozart, Beethoven, etc) never read your 21st-century textbook. If you want to know how they thought about the chord progressions they used, read some 18th-century texts instead! (Hint: for Haydn at least, figured bass was still "contemporary music notation" - hence "6/4 5/3".) – user19146 Mar 13 '17 at 4:38
  • @alephzero Sorry, where did I talk about a difference between a "Perfect Cadence" and a "Perfect Authentic Cadence"? – Pat Muchmore Mar 13 '17 at 8:25
  • @FrankBadertscher Sorry, just saw your question. Generally, a cadence is what it is based on the last two harmonies of the phrase, regardless of how the penultimate harmony is approached. For example, it's a PAC whether the V–I is preceded by a subdominant or not. However, the cadential 6/4 harmony really isn't a separate thing from the V—it isn't two chords—it's just a V that's been embellished. – Pat Muchmore Mar 13 '17 at 16:31

You are talking about a cadential 64 chord. A cadential 64 chord is one of the main four types of second-inversion triads. The four types include:

  1. Passing 64 (Ex. I6 - V64 - I)
  2. Arpeggiated 64 (Ex. I - 6 - 64 - 53)
  3. Auxiliary 64 (Ex. I - IV64 - I)
  4. Cadential 64 (Ex. I64 - V - I)

A cadential 64 is one of the most common dominant embellishment chords. We notate them as I64. It is used to emphasize the dominant-function V chord which must resolve to root position I. Such emphasization is called dominant embellishment.

Here is an SATB-type harmony exercise example: (SAT on treble clef, B on bass clef)

enter image description here

We can notice the authentic cadence at the end. It's extremely important to know that such chords have dominant function like V, and not tonic function. Notice the bass is scale degree 5 and the chord occurs after a subdominant-function IV chord. Also, please please PLEASE don't write an authentic cadence as I64 - I.

It's also very important to know that such dominant expansions are incredibly common to occur in authentic cadences that build up to dramatic climaxes. For example, the finale of Mahler's Symphony No. 1 contains such a passage:

enter image description here

At first, in the dynamic state of mf, we see a tonic-function I, and then a subdominant-function vi chord. Then we see a cadential I64, which is when a crescendo happens. Notice how the chord stretches out for 31/2 bars while the crescendo is in progress. Then we see an inverted V11. Realize how the crescendo extends from I64 to V11(inv.), the two dominant-function chords. This resolves to a tonic-function I in root position, which is when the dynamic finally changes into fff. It is extremely dramatic!

My answer will end up getting too long if I add more information, so I will give a link to https://en.wikipedia.org/wiki/Second_inversion.

  • 2
    In the Mahler example, why is that I64 not a passing 64? Why is that "inverted V11" not just a IV chord? – Richard Jun 4 at 16:58
  • 1
    @Richard - Good question! According to the orchestral score, it is an inverted V11. The attachment here somehow missed out some notes - including the arpeggio on the strings and the timpani roll. +1. (The point here was to introduce a dramatic way of embellishing the dominant) – Maika Sakuranomiya Jun 8 at 1:45
  • @Richard - anyways, the entire progression is I-vi-I6/4-V11(Inv)-I. – Maika Sakuranomiya Jul 4 at 23:21
  • 2
    Can the G in the strings be a pedal tone holding over from the I64 into the I at the end? That F in the bass is a chordal seventh that needs to be resolved down by step. Surely it's more correct to say the G is a pedal tone instead of calling this an eleventh chord in third inversion with a non-resolving chordal seventh (!)? – Richard Jul 6 at 0:47
  • 2
    A pedal tone is often in the bass, but not always. – Richard Jul 6 at 0:58

Not the answer you're looking for? Browse other questions tagged or ask your own question.