Odo of Arezzo or Abbot Oddo (fl. late 10th century) was a Medieval composer and theorist

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...

 who worked in Arezzo

Arezzo

Arezzo is a city and comune in Central Italy, capital of the province of the same name, located in Tuscany. Arezzo is about 80 km southeast of Florence, at an elevation of 296 m above sea level. In 2011 the population was about 100,000....

. Little is known about his life, except that he was an Abbot

Abbot

The word abbot, meaning father, is a title given to the head of a monastery in various traditions, including Christianity. The office may also be given as an honorary title to a clergyman who is not actually the head of a monastery...

 in Arezzo

Arezzo

Arezzo is a city and comune in Central Italy, capital of the province of the same name, located in Tuscany. Arezzo is about 80 km southeast of Florence, at an elevation of 296 m above sea level. In 2011 the population was about 100,000....

, working under Bishop

Bishop

A bishop is an ordained or consecrated member of the Christian clergy who is generally entrusted with a position of authority and oversight. Within the Catholic Church, Eastern Orthodox, Oriental Orthodox Churches, in the Assyrian Church of the East, in the Independent Catholic Churches, and in the...

 Donatus of Arezzo

Donatus of Arezzo

Saint Donatus of Arezzo is the patron saint of Arezzo, and considered a bishop of the city.A Passio of Donatus' life was written by a bishop of Arezzo, Severinus; it is of questionable historicity. He calls Donatus a martyr, though Donatus is described as a bishop and confessor of the faith in...

. Odo composed a tonary

Tonary

A tonary is a liturgical book in the Western Christian Church containing various chants which is organized according to the eight psalm tones of Gregorian chant. It may include antiphons from the Mass and Offices, as well as responsories and other chants...

 (a book of chant

Chant

Chant is the rhythmic speaking or singing of words or sounds, often primarily on one or two pitches called reciting tones. Chants may range from a simple melody involving a limited set of notes to highly complex musical structures Chant (from French chanter) is the rhythmic speaking or singing...

s which usually included antiphon

Antiphon

An antiphon in Christian music and ritual, is a "responsory" by a choir or congregation, usually in Gregorian chant, to a psalm or other text in a religious service or musical work....

s and responsories

Responsory

-Definition:The most general of a responsory is any psalm, canticle, or other sacred musical work sung responsorially, that is, with a cantor or small group singing verses while the whole choir or congregation respond with a refrain. However, this article focuses on those chants of the western...

) with a discussion of modes

Musical mode

In the theory of Western music since the ninth century, mode generally refers to a type of scale. This usage, still the most common in recent years, reflects a tradition dating to the middle ages, itself inspired by the theory of ancient Greek music.The word encompasses several additional...

, which survives in 20 manuscripts, four of which contain attributions to Odo. In several of the manuscripts a prologue ascribed in three out of six to Odo is entitled "Formulas quas vobis".

A Dialogus de musica has been mistakenly attributed to Odo of Arezzo.