The Optical Neume Recognition Project
A tool to investigate early staff-less music notation

Ven Venite et videte locum ubi positus erat dominus alleluia alleluia (cao5352)
St. Gallen, Stiftsbibliothek, Cod. Sang. 390, p. 32 (


The earliest form of Western musical notation that can still be deciphered today is made up of discrete signs called neumes. Neumes were written over the top of lines of text, in order to show how each syllable of the word should be sung. The earliest examples of these neumes are found in Gregorian chant manuscripts, which were written in monasteries, beginning in the 9th century. In the earliest examples of neumes, only select chants were notated, probably because they were different in some way from the rest of the repertory which would have been memorized. The earliest fully-notated manuscripts date from the beginning of the 10th century. The three earliest surviving books containing the year’s liturgical cycle are: Chartres, Bibliothèque Municipale 47, Laon, Bibliothèque Municipale 239 and St. Gall, Stiftsbibliothek Cod. Sang. 359.

Neume signs were not intended to be read and performed at sight, but rather, they remind the singer of a melody he is already familiar with. Neumes do not represent exact pitches (i.e., A = 440Hz) or musical intervals (i.e., a perfect fifth), the way modern notation does. Rather, they indicate how syllables of text are to be sung to a particular pitch, or sometimes groups of two, three, or even more pitches. The pitch-relationship depicted might be, for example, ‘lower pitch — higher pitch’ or ‘lower pitch — medium pitch — higher pitch’ and also indicate aspects of musical phrasing and articulation through their appearance on the page. For example, a neume representing two pitches in a single stroke denotes two musically joined notes sung on the same syllable of text. Unlike modern musical notation, neumes are not written on a vertical axis (i.e., musical staff) to show relative pitch height. They are usually written on a more or less horizontal axis directly over the sung text.

The set of basic neume signs is small. The figure below gives examples of the most common neume signs along with their Latin names and musical meanings. All images of neumes on this page are taken from binarized images of sample folios from St. Gallen Stiftbibliothek, Cod. Sang. 390 / 391 and are used with permission.

Virga Virga Single pitch or Higher pitch
Punctum Punctum Single pitch or Lower pitch
Tractulus Tractulus Single pitch or Lower pitch
Pes Pes Lower pitch — Higher pitch
Clivis Clivis Higher pitch — Lower pitch
Torculus Torculus Lower pitch — Higher pitch — Lower pitch
Porrectus Porrectus Higher pitch — Lower pitch — Higher pitch
Scandicus Scandicus Lower pitch — Medium pitch — Higher pitch
Climacus Climacus Higher pitch — Medium pitch — Lower pitch

In addition to these basic signs, there are special signs and combinations of signs which make up a varied and complex repertory of glyphs. Their interpretation is a highly specialized semiological pursuit within the discipline of medieval musicology.

From their very beginnings, neume signs showed overall similarities in shape but differences in rendering according to scribal traditions. It is therefore possible to categorize them according to regional styles. The regional styles originating in southern Germany and the middle of France are typically thought to be the oldest, although a particular type of neumes from the Laon region show a kind of ‘Paleofrankish’ notation which is thought to have appeared at the same time as the German and French neumes.

We have chosen to focus on the well-known sub-type of German neumes: St. Gall notation. These neumes first became the subject of semiological interest at the turn of the 20th century, when a facsimile edition of a 10th-century, mass book written in the abbey of St. Gall (Switzerland) became the first volume of the Paléographie musicale series. Le Codex 339 de la Bibliothèque de Saint-Gall (Xe siècle), Antiphonale missarum sancti Gregorii. Paléographie musicale I/I (Solesmes, 1889; reprint: 1992) This publication signalled the beginning of intense scholarly interest in St. Gall neumes, lead by Eugène Cardine, who was instrumental in founding Gregorian Semiology as a discipline within Medieval Musicology. A good summary of Cardine’s involvement and bibliography is found in Luigi Agustoni’s ‘Die Gregorianische Semiologie und Eugène Cardine’, Beiträge zur Gregorianik 1 (1985), 9-22. For the purposes of this project, it is important to use neumes for which there is a large body of previous research. A taxonomy of St. Gall neumes can be found in Cardine’s Semiologie Gregorienne.Eugène Cardine, ‘Semiologie Gregorienne’ Études Grégoriennes XI (Solesmes, 1970). The manuscripts used to develop this taxonomy are all notated with St. Gall neumes: St. Gallen Stiftbibliothek, Cod. Sang. 359; Einsiedeln 121; Bamberg, Staatl. Bibl. lit. 6; St. Gallen Stiftbibliothek, Cod. Sang. 339; and the manuscript chosen for the present project, St. Gallen Stiftbibliothek, Cod. Sang. 390 / 391. He identifies 24 signs and discusses each individually, pointing out that various graphical changes may be made to indicate particular aspects of performance.

One significant graphic change to the appearance of basic neume signs is liquescence. To indicate liquescence, the beginning or end of the neume is more elongated and curved compared to the basic shape, as shown in the figure below. Liquescent neumes usually occur where spoken syllables must be connected in a fluid, soft manner. These signs also give significant indications for linguistic historians. They are found in texts containing sonant consonants such as ‘m’, ‘n’, ‘l’, or ‘r’, but may also be found at diphthongs or surd consonant combinations, such as ‘b + vowel’, ‘t + vowel’ or ‘d + vowel’. They also occur in consonant groupings ‘gn’ (e.g. ‘magni’, ‘regni’), at an ‘m’ between two vowels (e.g., ‘petra melle’, ‘altissimus’), at a ‘g’ immediately before a bright, forward vowel (e.g., ‘regit’) and at a ‘j’ between vowels (e.g., ‘ejus’, ‘cujus’). Specific aspects of the correct musical interpretation of these liquescents remain uncertain.

The table below lists the most common neume forms beside their liquescent alternatives, illustrating the graphic difference between the common neume form and the liquenscent (and not its musical interpretation.)

Basic Form Liquescent Form
Virga Virga Basic Virga Liquescent
Pes Pes Basic Pes Liquescent
Clivis Clivis Basic Clivis Liquescent
Torculus Torculus Basic Torculus Liquescent
Porrectus Porrectus Basic Porrectus Liquescent

Another graphic addition to the basic neume sign is a small, horizontal stroke called an episema. Episemas usually indicate a lengthening or stress on the pitch indicated. In neumes representing two or three pitches, the episema will be found on the relevant part of the neume. The example below shows the basic clivis, indicating two descending pitches, and compares this to a clivis with an episema on the first (higher) of the two pitches and a clivis with an episema on the second (lower) of the two pitches.

Basic Episema on 1st, higher pitch Episema on 2nd, lower pitch
Clivis Clivis without episema Clivis with episema on first pitch Clivis with episema on second pitch

The final type of addition to the St. Gall neumes are ‘significative letters’. These are lower-case letters added just above the neume signs to indicate rhetorical or rhythmic features of the chant. While significative letters are found in other kinds of neumes as well, researchers are fortunate to have a 10th-century letter written by a monk at St. Gall which lists the musical meanings of each of these letters at his abbey. The letters usually stand for a Latin word, indicating how the neume is to be sung: ‘t’ for ‘tenete’ (held); ‘c’ for ‘celeriter’ (quickly); ‘a’ for ‘altius’ (high), and so on.

St. Gall notation is therefore made up of neumes above the syllables of sung text as discrete signs. The basic set of neumes (ut supra) and some combined forms indicating gestural or perhaps rhythmic properties may be altered in appearance to reflect textual characteristics and performance instructions, and significative letters containing further information about the melody may be added. A representative sample of a Gregorian chant written at the St. Gall scriptorium around the year 1000 is shown below St. Gallen, Stiftsbibliothek, Cod. Sang. 390, p. 61 (

St Gall sample of Gregorian chant