Solmization
The system of note syllables do-re-mi.
What it means
Solmization is the designation of notes by syllables that are sung: do, re, mi, fa, sol, la, and, added later, si or ti. Its purpose is to ease sight-singing by assigning every degree its own name in sound. The system arose in the eleventh century, transmitted in connection with Guido of Arezzo, who obtained the syllables from the opening syllables of the lines of a Latin hymn.
Musical use
The original system rested on hexachords, overlapping six-note rows in which the semitone always lay between mi and fa. When crossing the six-note range, one changed into the next hexachord through the so-called mutation. Later the seventh syllable was added, and the system was converted to the octave.
Today two conceptions stand side by side. With movable do, do designates the tonic of the prevailing key in each case, so that the syllables name degrees: ti is always the leading tone, sol always the fifth. This trains relative hearing and makes the function of a note immediately felt. With fixed do, by contrast, do always designates the same note — in the Romance-language world the syllables are simply the note names, and do corresponds to German C.
Solmization is often supplemented by the Kodály hand signs, which assign a hand shape to every syllable and make the melody visible in space.
A distinction is made between absolute and relative solmization. In absolute solmization, fixed do, the syllables are connected with fixed pitches, as in France and Italy. In relative solmization, movable do, they designate the degrees of a key, as in the Tonic Sol-fa method and with Kodály. Both procedures train inner hearing, but in different ways: one trains awareness of pitches, the other of relations.
Performance practice
If you want to train your ear, choose movable do and keep to it; switching between the two systems confuses more than it helps. Sing short melodies on syllables before you play them, and watch especially the semitone between ti and do as well as between mi and fa. And use the hand signs in group teaching — they make degrees visible and tangible.