This tutorial explains how to add sound effect to your Squash & Stretch animations in After Effects
Each behavior of Squash and Stretch comes with a variety of sound designs. Just select one of them and then apply the behavior as usual.
The sound designs consist of several sound layers such that you have full control over the volume and timing of each individual sound.
In the Preferences of Squash & Stretch you can choose to shy or precompose the sounds automatically to keep your composition clean and structured. Also Squash & Stretch can copy the audio files to your project folder on import if you prefer to keep all sources in your project folder.
Of course, you have access to the individual audio files, too. This allows you to use Squash & Stretch like a normal stock sound effects collection. Already the free version contains almost 100 sound effects!