Was the audio file embed into the scene asset bundle file?

In my scene, it referenced a prefab that has a `MonoBehaviour` class with an `AudioClip` member. After build the scene to the asset bundle file for Android, I found the file size is about **2.6MB**. Then I remove all audio files and build the scene again, the file size is about **170KB**. I think the scene asset bundle just has a reference with the prefab file, and the content of the prefab file should be in another asset bundle file. Why is the audio file embed into the scene asset bundle? Has anyone meet this situation. Please help me to solve this problem? Thank you very much.