Hearing audio while scrolling

I watched a tutorial on lipsyncing recently and i noticed that when the person scrolled through the timeline with the mouse, the audio in the timeline would play when he moved and stop where he stopped, making it pretty easy to find where certain sounds are. But when i put audio on the timeline and do the same thing, the audio doesn’t play. I dont know if this matters or not but I am using Flash 8 and the tutorial was for Flash MX. If anyone knows how i can make audio play while I scroll through the timeline please let me know. Thanks.