The Sounds of Music
In the simplest terms music can be described as the juxtaposition of two : pitch and , usually called melody and rhythm. The unit of musical organisation is the note - that is, a sound with pitch and . Music thus of combinations of notes that appear (melody) or simultaneously (harmony) or, as in most Western music, both.

Melody
In any musical system, the of melody notes from a prescribed set called a scale, which is actually a group of pitches separated by (the distances in pitch between notes). Thus, the scale of 18th- and 19th-century Western music is the chromatic scale, represented by the piano keyboard with its 12 equidistant notes per octave; composers from these notes to produce all their music. Much Western music is also based on diatonic scales - those with seven notes per octave, as by the white keys on the piano keyboard. In the diatonic scales and in the pentatonic scales - those with five notes per octave, most often to the black keys on the piano - that are common in folk music, the notes are not equidistant.

can be measured in units called cents, 1,200 per octave. The typical of Western music are multiples of 100 cents (semitones), but in other musical of about 50, 150, and 240 cents, for example, are also found. The human ear can distinguish as small as 14 cents, but no that small seems to play a in any musical system.

Rhythm
The handling of time in music is expressed through such as the lengths of notes and the interrelationships among them; relative degrees of on different notes; and, in particular, metre.

Most Western music is built on a of regularly recurring beats - that is, a metrical . This may be (as in the beating of the bass drum in popular music and marching bands), or it may be (often in symphonic or instrumental music). The three most common metres in Western music are units of four beats (with main on the first beat, secondary on the third beat); of three beats ( on the first); and of six beats ( on the first, secondary on the fourth). , these metres are called o, k, and u. Far greater is found, however, in 20th-century Western art music, Indian music, and West African drum ensembles. , much music is without regular metre, as in some genres in India and the Middle East, and in Christian, Jewish, Islamic, and Buddhist liturgical chant.

Other Elements
The organisation given to simultaneously produced pitches is also of great importance. Two or more voices or instruments performing together may be as producing independent but related melodies (counterpoint); or the may be on how the groups of simultaneous notes (chords) are related to one another, as well as on the progression of such groups through time (harmony). Timbre, or sound quality, is the musical that accounts for the differences in the characteristic sounds of musical instruments. Singers have a variety of timbres as well, each by such as vocal , nasality, amount of accentuation, and slurring of pitch from one note to the next.

One characteristic of music everywhere is its transposability. A tune can be performed at various pitch levels and will be recognised as long as the relationships among the notes remain . , rhythmic patterns can almost always be as , whether executed quickly or slowly. These of music are used to organise pieces extending from simple melodies using a scale of three notes and lasting only ten seconds (as in the simplest tribal musics) to highly works such as operas and symphonies. The organisation of music the presentation of basic material that may then be repeated or with changes (), may with other materials, or may continually to present new material. Composers in all societies, often unconsciously, strike a balance between unity and variety, and almost all pieces of music contain a certain amount of repetition - whether of notes, short groups of notes (), or longer units such as melodies or chord (often called ).