In music

Music theory

Music theory is the study of how music works. It examines the language and notation of music. It seeks to identify patterns and structures in composers' techniques across or within genres, styles, or historical periods...

, a ninth is a compound interval

Interval (music)

In music theory, an interval is a combination of two notes, or the ratio between their frequencies. Two-note combinations are also called dyads...

 consisting of an octave

Octave

In music, an octave is the interval between one musical pitch and another with half or double its frequency. The octave relationship is a natural phenomenon that has been referred to as the "basic miracle of music", the use of which is "common in most musical systems"...

 plus a second.

Like the second, the interval of a ninth is classified as a dissonance in common practice

Common practice period

The common practice period, in the history of Western art music , spanning the Baroque, Classical, and Romantic periods, lasted from c. 1600 to c. 1900.-General characteristics:...

 tonality

Tonality

Tonality is a system of music in which specific hierarchical pitch relationships are based on a key "center", or tonic. The term tonalité originated with Alexandre-Étienne Choron and was borrowed by François-Joseph Fétis in 1840...

. Since a ninth is a larger than a second, its sonority level is considered less dense.

Major ninth

A major ninth is a compound musical interval spanning 14 semitone

Semitone

A semitone, also called a half step or a half tone, is the smallest musical interval commonly used in Western tonal music, and it is considered the most dissonant when sounded harmonically....

s, or an octave plus 2 semitones. If transposed into a single octave, it becomes a major second or minor seventh. The major ninth is somewhat dissonant in sound.

Transposition

Some common transposing instrument

Transposing instrument

A transposing instrument is a musical instrument for which written notes are read at a pitch different from the corresponding concert pitch, which a non-transposing instrument, such as a piano, would play. Playing a written C on a transposing instrument will produce a note other than concert C...

s sound a major ninth lower than written.
These include the tenor saxophone

Tenor saxophone

The tenor saxophone is a medium-sized member of the saxophone family, a group of instruments invented by Adolphe Sax in the 1840s. The tenor, with the alto, are the two most common types of saxophones. The tenor is pitched in the key of B, and written as a transposing instrument in the treble...

, the bass clarinet

Bass clarinet

The bass clarinet is a musical instrument of the clarinet family. Like the more common soprano B clarinet, it is usually pitched in B , but it plays notes an octave below the soprano B clarinet...

, the baritone

Baritone horn

The baritone horn is a member of the brass instrument family. The baritone horn has a predominantly cylindrical bore as do the trumpet and trombone. A baritone horn uses a large mouthpiece much like those of a trombone or euphonium, although it is a bit smaller. Some baritone mouthpieces will sink...

/euphonium

Euphonium

The euphonium is a conical-bore, tenor-voiced brass instrument. It derives its name from the Greek word euphonos, meaning "well-sounding" or "sweet-voiced"...

 when written in treble clef, and the trombone

Trombone

The trombone is a musical instrument in the brass family. Like all brass instruments, sound is produced when the player’s vibrating lips cause the air column inside the instrument to vibrate...

 when written in treble clef (British brass band

Brass band (British style)

A British-style brass band is a musical ensemble comprising a standardised range of brass and percussion instruments. The modern form of the brass band in the United Kingdom dates back to the 19th century, with a vibrant tradition of competition based around local industry and communities...

 music).

When baritone/euphonium or trombone parts are written in bass clef or tenor clef they sound based.

Minor ninth

A minor ninth (m9 or -9) is a compound musical interval spanning 13 semitones, or 1 semitone above an octave (thus it is enharmonic

Enharmonic

In modern musical notation and tuning, an enharmonic equivalent is a note , interval , or key signature which is equivalent to some other note, interval, or key signature, but "spelled", or named, differently...

ally equivalent to an augmented octave). It is a type of extended minor seventh

Minor seventh

In classical music from Western culture, a seventh is a musical interval encompassing seven staff positions , and the minor seventh is one of two commonly occurring sevenths. The minor quality specification identifies it as being the smallest of the two: the minor seventh spans ten semitones, the...

. If transposed into a single octave, it becomes a minor second or major seventh. The minor ninth is rather dissonant in sound, and in European classical music, often appears as a suspension. Béla Bartók

Béla Bartók

Béla Viktor János Bartók was a Hungarian composer and pianist. He is considered one of the most important composers of the 20th century and is regarded, along with Liszt, as Hungary's greatest composer...

 wrote a study in minor 9ths for piano. The fourth movement (an intermezzo

Intermezzo

In music, an intermezzo , in the most general sense, is a composition which fits between other musical or dramatic entities, such as acts of a play or movements of a larger musical work...

) of Robert Schumann

Robert Schumann

Robert Schumann, sometimes known as Robert Alexander Schumann, was a German composer, aesthete and influential music critic. He is regarded as one of the greatest and most representative composers of the Romantic era....

's Faschingsschwank aus Wien

Faschingsschwank aus Wien

Faschingsschwank aus Wien is a solo piano work by Robert Schumann, his Op. 26. Schumann began composition of the work in 1839 in Vienna...

, is a constructed to feature prominent notes of the melody

Melody

A melody , also tune, voice, or line, is a linear succession of musical tones which is perceived as a single entity...

 a minor ninth above the accompaniment. Alexander Scriabin

Alexander Scriabin

Alexander Nikolayevich Scriabin was a Russian composer and pianist who initially developed a lyrical and idiosyncratic tonal language inspired by the music of Frédéric Chopin. Quite independent of the innovations of Arnold Schoenberg, Scriabin developed an increasingly atonal musical system,...

's sonata no. 9, 'black mass' is based around the interval of a minor ninth, creating an uncomfortable and harsh sound.

Augmented ninth

An augmented ninth is a compound musical interval spanning 15 semitones, or 3 semitones above an octave. Enharmonically equivalent to a compound minor third, if transposed into a single octave, it becomes a minor third or major sixth. It is a consonant interval.

Ninth chords

Three types of ninth chords may be distinguished: dominant (9), major (M9), and minor (m9). They may easily be remembered as the chord quality of the seventh does not change with the addition of the second scale degree, which is a major second in both major and minor

Major and minor

In Western music, the adjectives major and minor can describe a musical composition, movement, section, scale, key, chord, or interval.Major and minor are frequently referred to in the titles of classical compositions, especially in reference to the key of a piece.-Intervals and chords:With regard...

, thus:

0 4 7 t + 2 = dominant seventh

Dominant seventh chord

In music theory, a dominant seventh chord, or major minor seventh chord,is a chord composed of a root, major third, perfect fifth, and minor seventh. It can be also viewed as a major triad with an additional minor seventh...

 + ninth = dominant ninth chord
0 4 7 e + 2 = major seventh

Major seventh chord

In music, a major seventh chord is any nondominant seventh chord where the "third" note is a major third above the root.Most typically, major seventh chord refers to where the "seventh" note is a major seventh above the root . This is more precisely known as the major/major seventh chord, and it...

 + ninth = major ninth chord
0 3 7 t + 2 = minor seventh

Minor seventh chord

In music, a minor seventh chord is any nondominant seventh chord where the "third" note is a minor third above the root.Most typically, minor seventh chord refers to where the "seventh" note is a minor seventh above the root...

+ ninth = minor ninth chord

The dominant ninth (V₉) is a dominant seventh plus a major or minor ninth.