After figuring out all the sound tricks in AE, i finished my composition and rendered it to a final avi format video...but the sound just plays scratchy. It's only a 2 seconds audio (in mp3 format, don't know if it matters), and in the audio preview it plays well..i just can't understand why it won't work after rendering.
You should never use compressed audio, especially MP3's in AE. Convert the sound file to wav or aif. When rendering final output either choose uncompressed for the audio options or open up your AE project in Adobe Media encoder and use one of the default compressed settings. This will solve your problems.