We love the sound of laughter - but only if it's spontaneous and open mouthed, a new study reveals today. Scientists discovered laughter is only truly infectious if its an open-mouthed 'ha-ha' rather ...
Add Yahoo as a preferred source to see more of our stories on Google. Hearing an eerie, laugh-like sound coming from the backyard may sound like the beginning of a scary movie, but for one Los Angeles ...
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