Motion by Descending Third

Question 1

Motion by descending third

Answer 1

• Although the descending fifth was not invertible (ascending fifth), the descending third if often found ascending as well
• the primary use of this motion is descending
• the complete chain of descending thirds:
• • Major: I - vi - IV - ii - viio - V - iii - I
• • Minor: i - VI - iv - iio - viio (or VII) - V - III - i
• the beginning of the chain is used much more often than the end
• the mediant chord is the cause for the lack of use
• • V - iii and iii - I are not common
• I - vi, vi - IV - ii, and ii - viio are very common
• ii - viio can be found in the predominant to dominant area because the vii/o7 and the viio7 can be a dominant substitute
• voice leading for descending third pairs holds two common tones, moves the other voices to double the root
• the ascending third chains are also present in music
• the is mostly due to the extension of tonic (I - iii), predominant (ii - IV) or dominant (V - viio)
• complete chains are:
• • Major - I - iii - V - viio - ii - IV - vi - I
• • Minor - i - III - V - viio (or VII) - iio - iv - VI - i

Question 2

although descending thirds are more common, ascending thirds are also sometimes found in music

Answer 2

• true

Question 3

complete the descending third cycle, in a major key

I - __ - IV - __ - viio - __ - iii - __

Answer 3

• vi; ii; V; I

Question 4

why do we more often hear descending thirds rather than ascending thirds?

Answer 4

• the progression of descending thirds makes more logical musical sense

Question 5

in either ascending or descending thirds in minor keys, which chord has two possible qualities?

Answer 5

• viio/VII

Question 6

the main use for ascending thirds is to ______

Answer 6

• extend tonic, predominant, or dominant function