People snort when they laugh because they are also exhaling through the nose. The snorting sound, similar to snoring, is caused by an obstruction in the airway as the breath is exhaled.
Researchers have studied laughter to find a range of sounds produced by people as they laugh. A United States study found that the type of laugh often varies by gender. Women tend to laugh in a sing-song or voiced manner about half the time while men grunted or snorted about two-thirds of the time. Specifically, men snort about a third of the time while women snort about one-quarter of the time.