changing tempo of the song

I am newbie to Sonar and I want to ask how to change the tempo of the audio. I import an audio file into Sonar. When I change the tempo on the panel, the ruler changes but the audio is not sped up when played. And the effect I want is something like time warp, speeding up the audio file without changing the pitch. (sacrificing the quality) I want to ask if sonar has this function? Thanks in advance.