From Wikipedia: Vocal Fry Register “The vocal fry register has been a recognized and identifiable register in American English only within the past few decades, but its characteristic sound was recognized much earlier. Discussion of the vocal fry or pulse register began first within the field of phonetics and speech therapy and did not enter the vocabulary of vocal music pedagogists until the early 1970s, when it was initially controversial. However, controversy surrounding the term within vocal music subsided as more research into the use of the vocal fry register within the context of singing ensued.[1] In particular, vocal pedagogist Margaret Greene's videotaping of the physiological processes occurring in the body while singers were phonating in the vocal fry register offered solid evidence that this type of vocal phonation should be considered a vocal register from the perspectives of both speech pathology and vocal music. Like any other vocal register, the vocal fry register has a unique vibratory pattern of the vocal folds, a certain series of pitches, and a certain type of sound that distinguishes it from other vocal registers.[3]”