A falsetto voice is a special way of speaking or singing. If a man tries to imitate a woman’s voice he does it by speaking in a falsetto voice. When a man sings with a falsetto voice it sounds high like a soprano. Actors do this sometimes, e.g. Robin Williams in the film "Mrs Doubtfire" or Kevin Clash when voicing the character Elmo in "Sesame Street" and Barry Gibb of the Bee Gees, with his R&B falsetto. Also, Kellin Quinn from the band sleeping With Sirens uses falsetto sometimes.