With the addition of changes and alteration for the situation, the sheer numerical data is phenomenal. There are two theories as to why they are included in the songs. They are a personal gift from the creator and known by and important only to the singer and creator. They are thought to convey the deepest expressions of heart and soul. Some of the characteristics of Navajo-Apache styles of singing include a light nasal singing style.
Vocal ranges are often mixed.
Songs are mostly unison, though there may be some responsal.