A stertor is a respiratory sound characterized by heavy snoring or gasping. It is caused by partial obstruction of airway above the level of the larynx and by vibrations of tissue of the naso-pharynx, pharynx or soft palate (this distinguishes it from stridor, which is caused by turbulent air flow below or in the larynx). It is low-pitched, non-musical, and occurs during the inspiratory phase only. In general terms it is a snoring or snuffly sound. Stertorous breathing will be audible during the post-ictal phase after a tonic-clonic seizure.