Music theory is a set of systems for analyzing, classifying, and composing music and the elements of music. Narrowly it may be defined as the description in words of elements of music, and the interrelationship between the notation of music and performance practice. Broadly, theory may be considered any statement, belief, or conception of music (Boretz, 1995). The academic study of music is called musicology.
Music theory generally attempts to reduce the practice of composing and playing into rules and ideas. Generally, music theory works are both descriptive and prescriptive, that is they both attempt to define practice and to influence later practice. Thus, music theory generally lags behind practice in important ways, but also points towards future exploration and performance. Musicians study music theory in order to be able to understand the relationships that a composer or songwriter expects to be understood in the notation, and composers study music theory in order to be able to understand how to produce effects and to structure their own works. Composers may study music theory in order to guide their precompositional and compositional decisions. Broadly speaking music theory in the Western tradition focuses on harmony and counterpoint, and then uses these to explain large scale structure and the creation of melody.
Music theory describes how sounds, which travel in waves, are notated, and the relationship between what is sounded, or played, is perceived by listeners. The study of how humans interpret sound is called psychoacoustics. In music these waves are not usually measured by length (or wavelength) or period, but by frequency.
Every object has a resonant frequency which is determined by the object's composition. The different frequencies at which the sound producers of most instruments vibrate are given by the harmonic series. The resonators of musical instruments are designed to exploit these frequencies. Different instruments have different timbres because of variation in the size and shape of the instrument.
Sounds can be classified into pitches, according to their frequencies or their relative distance from a reference pitch. Tuning is the process of assigning pitches to notes. The distance in pitch between two notes is called an interval. Notes, in turn, can be arranged into different scales and modes. The most common scales are the major and minor scales.
Rhythm is the arrangement of sounds in time. Metre divides time into regular intervals, called measures (or bars in British English). The time signature specifies how many beats are in a measure, and which kind of note lasts for one beat. Syncopated rhythms are rhythms in which normally unaccented beats are accented. Playing simultaneous rhythms in more than one time signature is called polyrhythm.
Melody combines notes pitches with rhythm. In a piece of music, the melody is the most identifiable theme. Melodies will often imply certain scales. Counterpoint is the study of combining and layering more or less independent melodies.
Harmony happens when two or more notes sound at the same time, although an unaccompanied melody can still imply harmony. Melodies are often structured around sequences of chords, called chord progressions.
- The Grove Dictionary of Music and Musicians is considered to be one of the best general reference sources about music.
- The AB guides, written by Eric Taylor, are published by the Associated Board of the Royal Schools of Music, famous for their graded music examinations.
- Boretz, Benjamin (1995) Meta-Variations: Studies in the Foundations of Musical Thought. Red Hook, New York: Open Space.
- Music Theory Online
- Computing in Musicology
- Journal of the Royal Musical Association
- NewMusicBox.org Theory Issue 48 - Vol.4, No.12, featuring an interview with Edward Cone
Contributors please read WikiProject Music terminology if you consider working on these subjects.