preutterance

Preutterance is a parameter used in singing-voice synthesis systems such as Vocaloid and UTAU that controls how much of the current phoneme is uttered before the note onset. It effectively shifts the timing of the phoneme relative to the musical note, allowing consonantal portions of syllables to begin before the note starts or after, depending on the value.

In practice, preutterance is typically expressed as a time offset (milliseconds) or as a proportion of the phoneme’s length. A larger preutterance value causes more of the consonant or initial sound to be voiced before the note attack, producing a crisper onset; a smaller value delays the onset. Preutterance is used in conjunction with postutterance, which governs how much of the phoneme remains after the note end, to shape the full realization of phonemes across note boundaries.

The concept helps singers' articulation feel natural when translating written lyrics into synthesized singing. It is especially relevant for handling plosives and fricatives at note boundaries, where timing inaccuracy can produce abrupt or staccato-sounding starts. While the exact implementation and value ranges vary by software, the underlying goal is consistent: align phoneme onset with musical timing to produce smooth, intelligible vocal performance.

See also: postutterance, phoneme timing, UTAU, Vocaloid.