Dr. B Music Theory Lesson 31 (Leading-Tone 7th Chord in Major)

TOPICS:
0:00 - 1) Leading tone 7th Chords 3rd most frequently used 7th Chord
0:51 - 2) Functions like viio/dominant and is dm7 sonority (half diminished 7th)
2:25 - 3) Resolves to I or V6/5
3:10 - 4) May have to double the 3rd of I chord to avoid parallel 5ths
5:09 - 5) don't use 4/2 (3rd inversion)
***Upon further consideration I'd like to change the reason I give in the video; I think the real reason 3rd inversion is so rarely used is how it has to resolve. Since the 7th is in the bass and must resolve down that means it would naturally go to V7, V or I6/4; only the V7 really works since you would be staying within a dominant function and shouldn't REDUCE tension before resolving! This is the same reason you find V go to V7 as vs. the opposite!
8:16 - 6) 2nd inversion functioning like Plagal cadence
EXAMPLES:
10:42 - root position
13:50 - moving to V6/5
15:10 - 1st inversion (why you can't go to tonic in root position)
17:06 - 2nd inversion
18:39 - other possibilities
19:52 - approaching and resolving the leading tone 7th chord

[shereeabram]

In the years I've watched youtube, your series is the only one I've subscribed. Thank you for taking the time to explain music theory clearly in a logical progression.

[waynegram]

Major keys the leading tone 7th chord vii is a HALF Diminished and in Minor Harmonic Keys the leading tone 7th chord vii is FULL diminished. Example C major would be a HALF Diminished leading tone 7th chord B-D-F-A, while the relative minor is A Harmonic Minor the FULL Diminished leading tone 7th chord would be G#-B-D-F.  If you try to use FULLY Diminished vii chords in Major keys like C major the 7th chord is B-D-F-Ab, there is an out of key note Ab that is not in the key of C major so you "can't" use a Fully Diminished leading tone 7th chord likewise if you're in the Key of A harmonic minor the HALF diminished leading tone 7th chord is G#-B-D-F#, which the F# is an accidental out of key tone that is not in the key of A harmonic minor. If you look at the Natural A Minor scale the leading tone vii chord is a Dominant 7th chord NOT a diminished 7th chord in the Natural minor scale so there is no link tied connecting a diminished chord to a natural minor scale. The Harmonic minor scale has a LINK that is connecting the harmonic minor scale to the vii FULLY Diminished 7th chord because of the Raised#7 degree. I have heard of classical composers using HALF diminished and Fully diminished chords for both lowered 7th degrees and raised 7th degrees in Minor scales, which doesn't make sense because the natural minor scale vii chord is a Dominant 7 chord and NOT a diminished 7th chord which if you try to use the lowered 7th degree in a minor key it will be a dominant 7th chord not a diminished 7th chord. In Major keys classical composers will also switch back and forth using both HALF and FULLY diminished chords for the vii leading chord in major. This doesn't make sense because if you're using fully diminished leading tone chord in a major key the 7th chord tone of the fully diminished chord will have an accidental out of key note that is not related to the original key. For me its very confusing why the classical composers are switching back and forth between HALF diminished and FULLY diminished vii chords in major keys as well as in minor keys they are also switching back and forth between HALF and FULLY diminished vii chords on the lowered 7th degree and raised 7th degree. Maybe you can make more sense into trying to figure it out or they are breaking the rules.

[patriciaverso]

In 6:25, isn't that the case for all 4-2 chords, that they have a M2, a P4 and a m6? Why is there a problem only with the viiø42?
And thanks for the lecture again... they just get better and better :)

[jacobruiz]

Is the vii fully diminished chord used in major keys?