Humdrum lab 8
Chorck is a chorale-syntax checking program for chorale textures.
[documentation for chorck](http://extras.humdrum.org/man/chorck)
Eight syntax rules are checked by the program, as defined in the music-theory textbook: . Tonal Harmony with an Introduction to Twentieth-Century Music by Stefan Kostka and Dorthy Payne:
- Parallel 5ths between two voices when moving to different pitch classes.
- Parallel Octaves between two voices when moving to different pitch classes.
- Contrary parallel 5ths -- when two voices move in parallel 5ths displaced by an octave.
- Unequal 5ths -- when the bass part and another voice move from dim 5ths to perfect 5ths or vice versa.
- Hidden 5ths -- when the soprano moves in similar motion with another voice and the soprano leaps to a perfect 5th with that voice.
- Hidden 8va -- when the soprano moves in similar motion with another voice and the soprano leaps to a perfect octave with that voice.
- Voice crossing -- when an inner voice goes above the soprano voice or below the bass voice.
- Open spacing -- when the interval between successive voices other than the bass exceeds an octave.
cint is a tool that extract counterpoint modules from polyphonic music.
The three-interval counterpoint module for stepwise rising parallel thirds is "3 2 3". this can be done as a filter in VHV:
!!!filter: cint -O --search "3 2 3"
The -O option collapses intervals greater than an octave to less than an octave, such as 10th (an octave plus a 3rd) being transposed to 3rds.