I have no idea what you mean by "it is playing slow motion without sound".
I'm guessing you're trying to play the video in the timeline by pressing the space bar. That's a rokie mistake. You must do a ram preview. Use the Preview Panel or select Composition>Preview>Ram preview. AE will render a ram preview and, if audio is turned on in the Preview Panel, you'll get audio. The preview will only play until you run out of ram.
AE is a compositing app. It's not for editing, it's for making cool shots and on occasion sequences.