Monophony
Music with a single voice.
What it means
Monophony is music with a single voice: one melody without accompanying voices. Even if many people sing the same melody at once, the texture remains monophonic; likewise if instruments play the melody along in octaves. The designation concerns the number of musical lines, not the number of performers. It differs from homophony in that there an accompaniment is added.
Musical use
Monophony is the oldest and most widespread form of musical texture worldwide. In Europe it includes Gregorian chant, the songs of the troubadours and Minnesänger, and a large part of folk music. Its richness lies not in harmony but in melodic writing, rhythm, tone colour, and the bond to language; the church modes, the fine ornaments, and the organization by the text are to be understood without a polyphonic context. Whoever hears such music with the harmonic conceptions of a later time misses its construction. From monophony, polyphony develops from the Middle Ages onward, without displacing it.
Performance practice
Shape monophonic music from the text and from the melodic organization, not from an imagined harmony. Sing with calm, closed tone production and sparing vibrato, so that the group blends. Breathe together at agreed points. Choose a comfortable register, since many sources give no absolute pitch. Resist the temptation to add accompaniments where the sources name none — if it is nonetheless wanted, make the decision recognizable.
Bear in mind that monophony does not mean poverty: melodic subtlety, ornamentation, rhythm, and the bond to the text carry this music, and an added harmony rather obscures it than enriches it. If an accompaniment is wanted, make the decision recognizable and keep it sparing. Shape from the text, sing with closed tone production and sparing vibrato, and breathe together at agreed points. Set the breathing places according to the units of meaning of the text.
Check whether an edition has silently added an accompaniment, because that fundamentally changes the perception of the melody.