Interval Size and Quality

Benjamin Wright
6 min read
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Study Guide Overview
This AP Music Theory study guide covers intervals, including their definition as the distance between two notes played harmonically or melodically. It details how to name intervals based on size and quality (major, minor, perfect, augmented, diminished). The guide also explains tritone, unison, and octave, provides shorthand notation, and discusses interval inversion. Finally, it offers tips for singing and recognizing intervals and touches on consonance and dissonance.
#AP Music Theory: Intervals - The Ultimate Study Guide 🎶
Hey there, future music maestro! Let's get those intervals down pat. This guide is designed to be your go-to resource, especially the night before the exam. We'll make sure you're not just memorizing, but truly understanding intervals. Let's dive in!
#What are Intervals?
An interval is simply the distance in pitch between two notes. Think of it as the musical measuring stick between any two sounds. Intervals are the building blocks of melodies, chords, and harmonies. They can be:
- Harmonic: Notes played simultaneously. 🤝
- Melodic: Notes played one after the other. ➡️
Understanding intervals is crucial for both melodic dictation and sight-singing on the AP exam. It's the foundation of everything else!
#Naming Intervals: Size and Quality
Intervals have two key components in their names:
- Size: The numerical distance between notes (2nd, 3rd, 4th, 5th, 6th, 7th, 8ve). Count the lines and spaces between the notes, including the starting and ending notes. For example, C to E is a 3rd (C-D-E).
- Quality: The specific type of interval (major, minor, perfect, augmented, diminished).
#Interval Types:
- Major (M): Found in a major scale. Think of the C major scale for reference: C-D (M2), C-E (M3), C-F (P4), C-G (P5), C-A (M6), C-B (M7), C-C (P8).
- Minor (m): One half step smaller than a major interval. For example, C to Eb is a minor 3rd.
- Perfect (P): Unison, 4th, 5th, and octave. These are considered very stable intervals.
- Augmented (A): A major or perfect interval increased by a half step. For example, C to E# is an augmented 3rd.
- Diminished (d): A minor or perfect interval decreased by a half step. For example, C to Ebb is a diminished 3rd.
Major Scale = Major Intervals (except P4, P5, P8). Use the major scale as your reference point. Any interval in a major scale is either major or perfect. Then, adjust from there!
#Visualizing Intervals
Caption: This image shows all intervals within an octave, from a unison to an octave. Notice how the size of the interval increases as you move up the scale.
Remember, intervals are always named from the lower note to the higher note.
#Special Intervals
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Tritone: An interval of three whole steps (A4 or d5). It's known for its unstable, dissonant sound. Often called the "devil's tone" in history! 😈
Caption: A tritone, shown here as an augmented fourth. It creates a very distinct, tense sound.
-
Unison: Two notes at the same pitch. 👯
Caption: A unison, where two notes are played at the same pitch.
-
Octave: An interval of eight notes. 8️⃣
Caption: An octave, where the higher note is twice the frequency of the lower note.
#Interval Shorthand
Intervals are often written using shorthand notation:
- M = Major
- m = Minor
- P = Perfect
- A = Augmented
- d = Diminished
Example: A perfect fifth is written as P5, a minor third as m3, and an augmented fourth as A4.
#Interval Inversion
Inverting an interval means flipping the notes. The lower note becomes the higher note, and vice versa. Here's the trick:
- Subtract from 9: Subtract the original interval number from 9 to get the new interval number (e.g., a 3rd becomes a 6th because 9-3=6).
- Opposite Quality: Major becomes minor, minor becomes major, augmented becomes diminished, and diminished becomes augmented. Perfect intervals remain perfect.
9-Rule: To invert, subtract from 9. Then flip the quality. (M↔m, A↔d, P stays P).
Example:
- The inversion of a M3 is a m6. - The inversion of a P5 is a P4. - The inversion of an A2 is a d7
#Singing and Recognizing Intervals
The AP exam will test your ability to:
- Recognize intervals by ear (melodic dictation).
- Sing intervals accurately (sight-singing).
#Tips for Practice:
- Do-Re-Mi: Use the solfège scale to help you hear and sing intervals.
- Song Associations: Connect intervals to familiar melodies. For example, a major second is the beginning of "Happy Birthday," and a perfect fourth is the start of "Here Comes the Bride". 🎵
Practice singing and recognizing intervals daily. Use online interval trainers and sing along with recordings. The more you practice, the better you'll get!
#Consonant and Dissonant Intervals
- Consonant Intervals: Stable, resolved sounds. Think of them as the "home base"
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