Modulation (music)
Introduction
Modulation in music is the process of changing from one key (tonal center) to another. This can be done in various ways, such as by using a common chord or pivot chord which is a part of both keys. Modulation can add interest or contrast, provide a means of joining sections of a piece, and create a sense of forward motion or narrative in the music.
Types of Modulation
There are several types of modulation, each with its own characteristics and uses in music.
Common Chord Modulation
Common chord modulation, also known as pivot chord modulation, involves using a chord that is common to the original key and the key to which you want to modulate. This chord serves as a 'pivot' between the two keys. For example, in the key of C major, an A minor chord could be used as a pivot to modulate to the key of E minor, as it is the vi chord in C major and the iv chord in E minor.
Direct Modulation
Direct modulation, also known as phrase modulation, is a type of modulation where the change of key occurs without any preparation. The new key is established immediately at the beginning of the new phrase. This type of modulation can be very dramatic and is often used for effect in both classical and popular music.
Enharmonic Modulation
Enharmonic modulation is a method of modulation that involves changing the key by reinterpreting a chord or note enharmonically. For example, the chord of G# major in the key of E major could be reinterpreted as Ab major, facilitating a modulation to the key of Eb major.
Sequential Modulation
Sequential modulation involves the repetition of a musical sequence at different pitch levels, using the same series of intervals. The sequence is often repeated at a pitch level that is not within the original key, which leads to a modulation to a new key.
Chromatic Modulation
Chromatic modulation is a type of modulation that involves the use of chromatic chords to transition from one key to another. This type of modulation is often used in Romantic music and can create a sense of fluidity and unpredictability.
Purpose and Effect of Modulation
Modulation serves several purposes in music. It can create contrast, add interest, and provide a sense of forward motion or narrative. Modulation can also be used to join different sections of a piece, or to create a sense of climax or resolution.
Contrast
Modulation can provide contrast in a piece of music. By changing the key, the composer can introduce new melodic and harmonic possibilities, which can help to keep the music interesting and engaging.
Interest
Modulation can add interest to a piece of music. The process of changing from one key to another can create a sense of surprise or novelty, which can help to maintain the listener's attention.
Forward Motion
Modulation can create a sense of forward motion in a piece of music. By changing the key, the composer can create a sense of progression or development, which can help to give the music a sense of direction.
Narrative
Modulation can contribute to the narrative of a piece of music. The change of key can symbolize a change in mood, setting, or character, helping to tell a story through the music.
Examples of Modulation in Music
Modulation is a common technique in many different styles of music, from classical to pop.
Classical Music
In classical music, modulation is often used to provide contrast and interest, and to join different sections of a piece. For example, in sonata form, which is a common form in classical music, the exposition often modulates from the tonic key to the dominant key, while the recapitulation returns to the tonic key.
Popular Music
In popular music, modulation is often used for dramatic effect. For example, it is common for the final chorus of a pop song to be transposed up a step (a technique known as a 'truck driver's gear change'), creating a sense of climax and excitement.