The Maori singing voice is reedy and slightly nasal, the women having more pleasing voices than the men. The women have a rich quality in the middle register but tend to shrillness in the high register. A most characteristic effect is produced when the women use the chest voice and sing in unison with the men, a practice which may be due to the difficulty the women experience in singing high notes with tight throat muscles, which is their normal method of voice production. Both sexes have a highly developed sense of rhythm which is shown in the dignified, slow-moving ritual chants as well as in the animation and precision of canoe and action songs. Group singing is more usual than solo singing, the leader setting the pitch and tempo and sometimes continuing with some meaningless syllables at the end of a section. It is considered essential to keep perfect unison in both melody and rhythm, and memory-lapses are regarded as an omen of evil. In some songs it is a common practice to end a verse with a sudden expulsion of the breath and a glissando slide of the voice on some such syllable as A! Ae! E! Ei! This effect is sometimes called “hianga”.