How to create and analyse chords in Music21

Summary

This video introduces the use of Python's Music21 library to work with chords, covering chord creation, manipulation, and analysis. It demonstrates how to define chords using pitch names, pitch classes, or existing note objects. The video also explores chord attributes, such as duration and harmonic insights like triads and seventh chords. Additionally, the 'chordify' function is explained for extracting chords from complex scores, using Beethoven's seventh string quartet as an example. The video highlights how Music21 can facilitate harmonic analysis, offering tools for deeper musical exploration.

Takeaways

• 😀 Music21 provides a dedicated class to represent and manipulate musical chords in Python.
• 😀 Chords can be created using a list of pitch names, pitch classes (integers), or pre-created note objects.
• 😀 The `add()` method allows adding new notes to a chord, and chords can be merged using this method.
• 😀 The `remove()` method lets us eliminate specific notes from a chord.
• 😀 By default, a chord has a quarter note duration, but this can be changed using the `duration` attribute.
• 😀 The `isTriad()` method checks if a chord is a triad, while `isSeventh()` determines if it’s a seventh chord.
• 😀 The `root` method identifies the root note of a chord, and the `commonName` attribute returns common names like major or minor triad.
• 😀 Music21's `chordify` method simplifies complex scores into a sequence of chords.
• 😀 The `chordify` function works by grouping all notes into chords based on vertical alignment in a musical score.
• 😀 Non-harmonic tones such as passing notes or suspensions may be present in the chords generated by `chordify`.
• 😀 The `chordify` method is useful for harmonic analysis but requires further investigation to determine true harmonic content.

Q & A

What is the primary function of the `Chord` class in music21?

The `Chord` class in music21 is used to represent and manipulate musical chords within Python code. It allows users to create chords, modify their contents, analyze their structure, and perform various harmonic analyses.

How do you create a chord in music21 using pitch names?

You can create a chord in music21 by passing a list of pitch names as strings to the `Chord` constructor. For example, `chord.Chord(['C4', 'E4', 'G4'])` creates a C major chord with specific pitches.

Can you create a chord using pitch classes in music21? How?

Yes, you can create a chord using pitch classes by passing a list of integers representing the chromatic scale, where 0 corresponds to C, 1 to C#, and so on. For example, `chord.Chord([0, 4, 7])` creates a C major chord using pitch classes.

What is the difference between using pitch names and pitch classes when creating a chord in music21?

Pitch names specify the exact pitches and their octaves, such as 'C4' for middle C, while pitch classes use integers from 0 to 11 to represent pitches relative to the chromatic scale, without specifying the octave.

How can you add additional notes to an existing chord in music21?

You can add notes to an existing chord using the `add()` method. For example, `my_chord.add('B4')` will add the note B4 to the chord.

How does the `add()` method work for combining two chords in music21?

The `add()` method can be used to combine two chords by passing the second chord as an argument. For example, `my_chord.add(other_chord)` will merge the notes from `other_chord` into `my_chord`.

What method would you use to remove a note from a chord in music21?

You can remove a note from a chord using the `remove()` method. For example, `my_chord.remove('E4')` will remove the note E4 from the chord.

What is the default duration of a chord in music21, and how can it be modified?

By default, the duration of a chord in music21 is a quarter note. You can modify the duration by setting the `duration` attribute, such as `my_chord.duration = duration.Duration(2)` to make it a half note.

What does the `isTriad` method check for in a chord object?

The `isTriad` method checks whether a chord consists of three notes that form a triad, which is a basic chord structure commonly found in harmony.

How does the `chordify` function work in music21, and what is its purpose?

The `chordify` function in music21 is used to distill a complex score, which may have multiple voices or parts, into a sequence of chords by grouping notes and rests that occur at the same time. This is useful for harmonic analysis and simplifying complex scores.