# How do I write a cadence without any context?

I am studying for my online RCM theory exam, and since I have no contact with my piano teacher I’ve been correcting with the answer book. My answers and the answers in the book are very different. I have followed all the instructions I can, but there is no other context within the exercise, as to wether to write a perfect authentic cadence, inverted cadence, etc. But in the answer book, there is only one right answer. What am I missing?! The question only asks to write an authentic cadence, does not specify what kind, and then says only one specific kind is right. Is this correct? Or are all types of cadence correct?

• You may find this site useful: musicnotes.com/now/tips/… Could you explain what you're writing vs what you're seeing in the answer book? I would expect a perfect cadence will be V(7)-I with the roots in the bass. Apr 5, 2020 at 3:00
• Yes. It would be really helpful if we could see the answer book. Apr 5, 2020 at 6:51
• Cadence names are different on each side of the pond. And can bring slight confusion. Posting the question and answer would be helpful.
– Tim
Apr 5, 2020 at 7:38
• Is your question how to get the right answer for the textbook or how to understand cadences? Post images of your answer and textbook if you want to know what's up with the textbook answer key. May 5, 2020 at 13:37

The names of cadences can vary, but the concepts don't.

First, identify a structural ending. For example, `V` to `I` is not a cadence... unless it actually ends some phrase or section. Look for phrase/section endings, then categorize their cadences.

Next, identify the two final chords. For all practical purposes the combinations are:

• `V` to `I` for the various authentic types
• and chord to `V` for half cadence
• `V` to `vi`for deceptive/interrupted types

...replace `I` with `i` and `vi` with `bVI` in minor.

Finally, the melodic movements of the bass and soprano voices provide the detail for specific types. I prefer scale degree notation using a circumflex `^` for this part.

Bass `^5` to `^1` and soprano something `...` to `^1` are the movements for perfect types. Sopranos `^1 ^7 ^1` or `^3 ^2 ^1` would both satisfy this type, it just needs to end on `^1`.

When the chords are `V` to `I` but the melodic movement is anything not bass `^5` to `^1` and soprano `...^1` then the cadence is some kind of imperfect type.

Half cadences are any bass movement to `^5` with the soprano providing any other tone of the dominant chord. On the whole - or at least in some generic sense - I think this chord should be a simple triad `V` and not a dominant seventh chord `V7`. The point being the simple triad is stable and hence better for the stop of a cadence. An ending like `...V6/V V` which then continues like `V V7...` is a typical example showing `V` is stable and `V7` is active. Some might say that example is a modulation to the dominant and a retransition back to the tonic key. Call it whatever. The point is to be sensitive to the quality of the final dominant chord in a half cadence and the treatment of the subdominant `^4` around it.

Deceptive cadences for all practical purposes are bass `^5` to `^6` with the soprano on some tone of the submediant `vi`.

The plagal cadence is `IV` to `I` and...

• really just a kind of codetta after an authentic cadence
• or strictly speaking not classical style

Essentially, cadences are about phrase endings with the bass moving to `^5`, `^1`, or `^6` with the soprano providing some root position harmonization above with a fair amount of freedom except using `^1` for emphatic endings. When inverted chords are involved the cadences are "weakened" to some degree, or depending on the phrasing might be better described as "cadential harmony."

Something I have never read in a basic textbook, but seems really important to the understanding of cadences is the placement and purpose of authentic type cadences within the structure of a composition. Superficially an authentic cadence is just an authentic cadence, but within a composition's structure I see three main purposes:

• establish a starting key
• confirm a modulating phrase ending in a contrasting key
• conclude in the original starting key

An opening often moves back and forth between `I` and `V` in a way that superficially might look like cadences, but is really best described as cadential harmony. This establishes a key. Obviously nothing is ending.

After establishing a key, a piece usually moves through some number of different, contrasting keys. The phrases involved modulate. These phrases seem to start in one key, but end in another. Often the passages use sequential harmony. An authentic cadence can end the phrase, but of course the music does not stop. In this sense the purpose of the cadence is not an ending so much as a confirmation the music is in a different key. After this confirmation the next phrase can immediately start up on new chords and modulate to yet another key. So, something starting in `C` major could then have a modulating phrase end like `...V7/ii ii` followed by another modulating phrase immediately abandoning the key of `ii`, like `...V7/vi vi`. The point is these cadences don't establish and continue in a new key. They confirm a key without continuing. You could say that they function like endings, but because the various keys are not the opening key of the piece the music continues.

That brings us to the concluding cadence. This seems straight forward. After the initial key is established, if you make a concluding cadence in that opening key, you're done. More than one cadence in the opening key should then be understood in terms or premature or redundant. Taken on the grand scale of a sonata, it's the recapitulation. After a concluding cadence, harmonic motion around the tonic - alternating `V` and `I` or `IV` to `I`, etc. - is likely to be considered a coda. Not really cadences, but an extension of the tonic chord.

All this may seem to have nothing to do with your question, except that you mentioned context. The context that really matter for understanding cadence is form and the structure of phrases. Simply categorizing cadences by two chords and some voicing details barely scratches the surface about the structural meaning of cadences.

When I learned harmony (in the UK), there were 4 types of cadence. Perfect was V-I. Imperfect rested on V. Plagal was IV-I, the 'Amen' cadence. And Interrupted was a frustrated Perfect, typically V-vi.

'Perfect' seems to have been re-named as 'Authentic'. Fair enough. And Authentic has two variants, 'Perfect Authentic' where the bass goes 5-1 and the top voice goes 7-8. And 'Imperfect Authentic' where at least one of those criteria isn't met. Imperfect Authentic has four sub-types.. heck, I'm tired of copying out the textbook. Read about them here: https://www.musicnotes.com/now/tips/cadences-in-music-theory-the-4-types-explained/

Right, got that.

If the question simply asks for an Authentic cadence, and there are no other factors (like a given melody line that DOESN'T go 7-8) write a Perfect Authentic one.