Microsoft’s filing states that “There are a variety of circumstances under which it may be desirable to quickly control a device without having to interact with a traditional user interface. For example, often mobile device users forget to set their mobile devices in a silent or vibrate mode and the device rings or makes sounds at an inopportune moment.”
The techniques described in Microsoft’s patent filing could be used for controlling an audio signal of the mobile device in response to a whacking of the mobile device.