One who authenticates their music by singing it.” These are vocalists with proficiency but have some gaps in their technique that would not be true of trained, professional vocalists. Their instruments are primarily a means to a musical end.  They are largely unacknowledged by critics for their vocal prowess, but their artistry is not dependent on it; it is mostly dependent on other aspects such as songwriting, dancing, or other instruments entirely. As such, they are not marketed as vocalists.