Chimps' laughter is more a breathy expiration and inspiration, like panting, and sounds more like ah ah ah. One theory puts forth that this is one reason humans have been unable to teach chimps to speak. Not just their vocal structure is to blame. Their laughter is produced differently. In discovering how chimps laugh, researchers learn about more than laughter.
Humans laugh mostly during conversation, rather than physical contact.
As you would expect, people are more likely to laugh in social contexts. Obviously, social situations increase laughter. But contrary to researchers' expectations, Provine observed that most laughter is in the context of conversation, not as a response to any structured attempt to provoke laughter. Laughter mostly follows such lame remarks. Many researchers concentrate on the audiences.