Unlike devices such as printers and hard disk drives, audio devices do not necessarily have to be shareable between applications. However, if applications exist (or will exist in the future) that access your audio hardware directly, you should write a VxD to prevent these applications from doing so while Windows is using the device. For an example VxD, see the Microsoft Sound System sample device driver.
Note Audio and video compression and decompression drivers, including ACM drivers, do not directly access hardware and therefore do not require VxDs.