Perfect fifth

Definition

A perfect fifth is a musical interval that spans five diatonic scale degrees and is defined by the frequency ratio of 3:2. This interval is significant in Western music as it forms the foundation of harmony and is a key component in tonal systems. The perfect fifth contributes to chord construction, establishing a sense of stability and consonance in music.

5 Must Know Facts For Your Next Test

1. The perfect fifth is formed by counting five scale degrees from the root note, including the root itself, which creates a harmonious sound.
2. In a major scale, the perfect fifth occurs between the first and fifth notes, such as C to G in C major.
3. This interval is crucial for building chords, as major and minor triads are constructed using the root, third, and perfect fifth.
4. The perfect fifth is perceived as one of the most consonant intervals, contributing to the sense of resolution in music.
5. In tuning systems, such as just intonation, the perfect fifth has a frequency ratio of 3:2, while in equal temperament it is slightly adjusted to fit the system's division of an octave.

Review Questions

• How does the perfect fifth function within musical harmony and chord construction?
  • The perfect fifth plays a vital role in musical harmony by establishing consonance and stability within chords. When constructing triads, such as major and minor chords, the perfect fifth is formed alongside the root note and the third. This combination creates a sense of completeness and balance in the chord, allowing it to function effectively within a tonal framework.
• Discuss the role of the perfect fifth in different tuning systems and how it impacts musical perception.
  • The perfect fifth varies in its representation across different tuning systems. In just intonation, it has a precise frequency ratio of 3:2, producing a clear consonant sound. In equal temperament, however, this interval is slightly altered to ensure that all keys are usable within a fixed tuning system. These differences can affect how musicians perceive harmony and consonance, with just intonation often yielding richer sound quality compared to equal temperament.
• Evaluate the significance of the perfect fifth in shaping tonal systems throughout music history.
  • The perfect fifth has been crucial in shaping tonal systems throughout music history as it serves as a foundational element in constructing scales and chords. Its consonance has made it a central feature in Western music theory, influencing how composers create tension and resolution. By establishing hierarchical relationships between pitches based on this interval, musicians have been able to develop complex harmonic structures that define various musical styles and genres over time.

Related terms

interval: An interval is the distance between two pitches, which can be measured in terms of scale degrees or frequency ratios.

tonal center: The tonal center, or tonic, is the pitch that serves as the home base of a piece of music, around which other pitches are organized.

consonance: Consonance refers to combinations of notes that sound stable and pleasant together, often characterized by simple frequency ratios.