How many letters does the top answer for “produced with vibration of the vocal cords” have?

The most common answer is sonant (6 letters).

Crossword clue: produced with vibration of the vocal cords

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

sonant 6 letters wn-def

a speech sound accompanied by sound from the vocal cords

voiced 6 letters wn-def

produced with vibration of the vocal cords