A throat-clear is a sound made at the back of the throat by tightly constricting the laryngopharyngeal tissues and vibrating the palatoglossal arch and the vocal folds while exhaling thru the nose; this may be done with the mouth slightly opened or completely closed.
Contents
The throat-clear is articulated as a single-syllable exclamation, written onomatopoeiacally as "hem"; or it may be articulated as a double-syllable sound, written as "ahem", which is expressed by inhaling slightly and then exhaling more forcibly.
Paralanguage
The deliberately executed throat-clear is a nonverbal, paralingual form of metacommunication (see Wikipedia article on Business Etiquette)(see Wikipedia article on Paralanguage section The Throat-Clear).
Upper respiratory
The throat-clear may be articulated consciously or unconsciously as a symptom of a number of laryngopharyngeal (upper respiratory tract) ailments.
Voice
Continual throat-clearing is a symptom of chronically dry vocal chords, caused by of insufficiently produced amounts of mucus due to inadequate amounts of water, and excessive amounts of caffeine and alcohol. (Texas Voice Center ENT)