While working in After Effects, you may want to use the more comprehensive audio-editing capabilities of Adobe Soundbooth or Adobe Audition to fine-tune your audio layers. You can use the Edit In Adobe Soundbooth or Edit In Adobe Audition command to start Adobe Soundbooth or Adobe Audition from within After Effects.
If you edit an audio-only file (for example, a WAV file) in Adobe Soundbooth or Adobe Audition, you make changes to the original file. If you edit a layer that contains both audio and video (for example, an AVI file), you edit a copy of the layer’s audio file.
If you’re editing an audio-only layer, choose File > Save to apply your edits to the original audio file, or choose File > Save As to apply your edits to a copy of the audio file. If you choose File > Save As, you need to reimport the copy of the file into After Effects.
If you’re editing a layer that contains both audio and video, choose File > Save As. After you save the file, import it into After Effects, add it to the composition, and mute the original audio in the audio-video clip by deselecting the Audio switch in the Timeline panel.