Tonus

What it means

Tonus is the Latin word for tone and is encountered in music theory in several meanings that are to be kept apart. It designates, first, the single tone; second, the whole-tone step — as distinct from semitonus, the semitone; third, a mode, which is why the church modes are also counted as toni; and fourth, a recitation formula of liturgical chant.

Musical use

The fourth meaning is the most practically tangible one. As a psalm tone, tonus designates the formula according to which a psalm or a liturgical reading is delivered: an opening, a reciting note on which the text is spoken-sung, a caesura in the middle of the verse, and a closing formula. Every mode has such a tone belonging to it, and the closing formulas have several variants, so that the connection to the following antiphon fits.

The third meaning explains why there is talk of eight toni when the system of church modes is meant — four authentic and four plagal, determined by finalis and range.

The second meaning is found in the description of scales and intervals; the Latin usage is encountered there above all in older theoretical literature and in scholarly accounts.

Whoever encounters the term in a source must therefore first check which of the meanings is intended — the context decides.

In the Middle Ages, tonus designated both a whole-tone step and a mode, that is, a church mode. The eight church tones were counted as tonus primus through tonus octavus. Alongside this, in psalmody tonus meant the recitation model according to which a psalm is sung, with initium, tenor, mediatio, and terminatio. The ambiguity of the word is, when reading medieval

Performance practice

When you are studying liturgical chants, practise the psalm formula separately from the text: first sing the turns of phrase securely, then lay the text upon them. The reciting note demands a constant pitch with a natural flow of speech — the most common difficulty is that it gradually sinks. And orient the stress by the word, not by a metric beat.