Someone who was laughing his happiness that can infect people around him laugh.Especially if done with the mouth open, because the width of the more easy for him to make other people laugh participate.

Wide-open mouth when laughing would produce laughter with a vowel sound and vibrations are stronger, such as “Ha .. ha .. ha ..”. Vocals like this do not arise when people laugh with his mouth open only half or even closed altogether.

Two researchers laughter, Michael Orwen from Georgia State University and Tobias Riede from the University of Utah tried to compare the effects of these 2 types of laughter. Riede Orwen and involved 28 students and uses 48 different types of sound recordings of people laughing.

The stronger the vibration and vocal in the laughter that was played, the more students who feel more relaxed or even laughed. While the laughter produced with the mouth closed like a grunt from the nose at least get a response.

The researchers suspect, this effect is triggered by differences in human ability to imagine things funny and enjoyable by the sound of laughter is heard. The ability is called with a passion for laughter is also likely to cause laughter can be contagious.

Belly laughs with his mouth wide open is generally triggered by things that are very funny, so who listen will also think about the same thing funny. Instead the trigger laughter with closed mouth is generally not funny, sometimes just a little innuendos that tickles.

“It is important to note that like any sound, laughter is always associated with situations where someone is in a positive mental state. Mental condition that can actually be contagious,” said Orwen as quoted by LiveScience, Friday (19/11/2010).