Utrecht Psalter psalm 21

Microtones and Neumes

The use of microtones was obviously common in diverse traditions of Gregorian Chant in the early Middle Ages. But what was their function? New Phd-project by Dutch musicologist Leo Lousberg aims to shed light on this; and promises to change the musical performances of early medieval Gregorian Chant in quite a new direction.

Utrecht Psalter detail from psalm 21 - Courtesy: Leo Lousberg
Courtesy: Leo Lousberg

It is said that the devil lies in the details. This is apparently the case when it comes to understanding some special signs, which were discovered in a manuscript from Montpelier in the mid 19th century. The signs, which were found in the letter string underneath the neumes, have since been the subject of a sometimes vicious debate among musicologists.

Microtones are intervals smaller than semitones and were part and parcel of the enharmonic genus as known from the Delphic Hymns from 138 -128 BC – for a recording of a suggested reconstruction see a video med a performance of the ensemble Kérylos. . Anyone, who listens to this, will immediately discover that the intervals shift markedly. To a Western ear some of these intervals will be perceived as “strange” or “false”. We may have the same experience, if we listen to Arabic or Indian music, which is full of such microtonal intervals.

But what about the Middle Ages? It appears, Gregorian chant also sported microtonal intervals; partly because it was part of the classical tradition, but other sources might have been inspiration from Byzantium or the Arab culture, prevalent around the Mediterranean. Secondly, the transmission of chant did not build on written transmission but was learnt and taught by heart by local cantors, who obviously might have been influenced by their wider musical network and personal tastes.

The invention of the staff

However, in the first decades of the 11th century Guido d’Arezzo invented the idea of placing the neumes on horizontal lines. This enabled the presentation of the intervals between pitches. Soon the staff with four lines was in full use and chant might be read from the antiphonaries and not just learned by listening.

In a more traditional context this development posed a dilemma for cantors working in the old tradition. The question was, how to mark the seemingly “odd” microtones, which did not fit well with the new schemata. New signs had to be added and we find them in manuscripts like for instance the so-called Utrecht fragments ‘University Library Utrecht, Ms. fr. 4.3’.

New “neumes”

Utrecht Psalter. Detail . Courtesy: Leo Lousberg
Courtesy: Leo Lousberg

Thus the traditional understanding of these “new” neumes is that they refer to microtones.

Recently, Leo Lousberg has questioned this general understanding. His approach is not so much whether the new signs/neumes represented microtonal pitches or intervals but rather, why they were applied. This moved the question to what the intended functionality of the sound was, which was connected to these signs.

His opinion is that the signs indeed represented microtones, but in addition had rhetorical functions. What might this mean?

According to Leo Lousberg “composers/and or performers (or should we call them melodic orators now?) seem to apply microtones in liturgical chants when highlighting affective or instructive expressions”. More precisely microtones were indicated whenever the text was supposed to “move” – in rhetorical context using the term “movere”; eg. whenever the text expressed fear, respect, praise and the cantor in charge wished to move the audience to experience it like this.

Rhetorical tool

Utrecht Psalter. Detail . Courtesy: Leo Lousberg
The detail is here presented with a text from the Tractus Deus deus meus. The text underlined and in bold is set on microtonal intervals. Courtesy: Leo Lousberg

The critical hypothesis here is that the neumes signalling the use of microtones have as their primary function to enhance certain text elements.. Imagine an orator, who raises his voice at a specific point in his text in order to make a certain mark in the minds of his audience inducing both fear or awe; and then imagine a cantor, wishing his music to raise the same feelings in the breast of the performers and audience; and in this instance using microtonal intervals to shock the audience into hearing specific bits of the text in a new way. The same signal was used to point the audience to words, explained in comments by church fathers like Augustine. Summarising, microtonal signals as rhetorical tools gave the listeners food for (religious) thought.

Another curious find is that certain illuminated scenes in the Utrecht Psalter (written in Reims around 820 – 830) seem to match with expressions highlighted by microtones in certain chants for Mass. This has prompted Leo Lousberg to talk about the possibility of identifying the “Soundtrack for an Illustrated Carolingian Psalter”.

Some of these propositions were first aired in the master thesis of Leo Lousberg. Currently he is affiliated researcher at ICON at Utrecht University and writing a doctoral thesis on the use of microtones as rhetorical tools.


Leo Lousberg graduated in 2013 cum Laude in Musicology and Medieval Studies. In 2014 he won the Utrecht History Prize, awarded for his essay on the “Decayed Utrecht Heritage: a 12th century antiphonary”. His prize-winning essay is part of his thesis ”Early 12th Century Utrecht Responsories: a quest for Musical Style Elements”. This short presentation of his work has been generously


The Utrecht Psalter has been digitized and generously shared with the public at a dedicated website: The Utrecht Psalter