The perfect Cadence Experience

[Musicologo]

Let's make a small experience, with a perfect cadence:

(The notes are written bottom to top, being the first one the bass note)

[f | f a c] [ g | f g b] [ c | e g c]

If we play these 3 chords we have a perfect cadence. Our ear can "feel" that.

Now, the experience... let's repeat the chords, but changing two bass notes.

[e | f a c] [ f# | f g b] [ c | e g c]

I don't know you guys, but I still have a "feeling" of perfect cadence when hearing these "chords".
Let's keep changing. This time one note of each chord.

[e | f g# c] [ f# | f g# b] [ c | e g# c]

Althoug somewhat akwards, my ear STILL recognizes a perfect cadence here.
Specially if we play the three examples in a row, all sounds too clear.

Now...

Why does this happen?
At which point the cadence is no longer "perfect"?
What are the key notes so that the "feeling" of cadence disappears? Will it ever disappear?

Intuitively I had an hunch that the bass would be crucial, however now I think that maybe only the bass note on the third chord might be... I dunno, make yourselves the experience and tell me about it!...

[buckshead]

I may be wrong but isn't it the B, the leading note that is causing the effect

[llatham]

I may be wrong but isn't it the B, the leading note that is causing the effect

I would tend to agree.

Just FYI,

In acedemic theory circles, usually a couple of types of cadences are recognized.

Authentic cadences are those that move from a Dominant function chord to a Tonic function chord.

V-I or V7-I is considered to be a "Perfect Authentic Cadence" when both chords are in root position, and the soprano (melody) note of the I chord is the Tonic pitch.

(this is constant in your examples by the way).

If both chords are in root position, but some other scale degree is in the soprano (3 or 5), it is called a "Root Position Imperfect Authentic Cadence".

If either or both chords are inverted, it's called an "Inverted Imperfect Authentic Cadence".

If the V is replaced by viio(7), then it's a "leading-tone Imperfect Authentic Cadence".

I've noticed that some authors (especially students studying in Britain) use the term "Perfect" to mean any Dominant to Tonic, but the texts I've used had called Dominant to Tonic "Authentic" instead. "Perfect" in those contexts refers to a specific voicing.

There are of course Plagal, Half, and Deceptive cadences as well. I've noticed some authors also refer to what some call "perfect", and what I'm calling "authentic" as "full". So they have Full Close and Half Close (or the word cadence for close) for our standard Perfet/Authentic and Half cadences.

One interesting one is when viio4/3 moves to I like so:

D - E
B - C
Ab -G
F - C

It combines the aspects of an Authentic cadence (V-I as B and D moving to C and E) and the Plagal cadence (IV-I as Ab and F move to G and C). Brahms and other Romantic perdiod composers were fond of this, and it's not unlike our modern IVm-I progression, or Dm6/F - C type progressions.

I wonder if you hear this one as "more perfect" or "more plagal"?

Best,
Steve

[Musicologo]

Many thanks. I think you both are right. Probaly I'm being "fooled" by the soprano line, and even If I play clusters in the bass line, since I keep the soprano line the same I will hear always that "perfect cadence feeling".

Steve, I believe that your example is plagal to my ear exactly because of the same reason.

playing [d2-b2-ab3-f4] [e2-c3-g3-c4] like you suggested, induced me into plagal feeling because of the f4-c4 movement I ear in the soprano voice.

To feel the perfect sense it would be more if I ear something like f4-g4 in the soprano line... does that make any sense to you?

[geroyannis]

At which point the cadence is no longer "perfect"?
What are the key notes so that the "feeling" of cadence disappears? Will it ever disappear?

I think the juice in your example is the sequence of chord tones:
[f c] [f b] [e c]

It will stop sounding "perfect" when you change any of these notes.

At least that's how I feel.