Nohvocals are classified into hyōshi-ai , or vocals matching the rhythm, and hyōsyi-awazu, or vocals not matching the rhythm. The vocals in hyōshi-ai are basically structured with a unit of eight beats, called "honji." As well as honji, other units include "tori" with four beats, "okuri" with two beats, and "kataji" with six beats. Their use is based on the number of syllables and whether there is a melody or not.