In linguistics, creaky voice (sometimes called laryngealisation, pulse phonation, vocal fry, or glottal fry) is a special kind of phonation in which the arytenoid cartilages in the larynx are drawn together; as a result, the vocal folds are compressed rather tightly, becoming relatively slack and compact. They vibrate irregularly at 20–50 pulses per second, about two octaves below the frequency of normal voicing, and the airflow through the glottis is very slow. Although creaky voice may occur with very low pitch, as at the end of a long intonation unit, it can occur with any pitch.