External sound devices Devices such as the Covox Speech Thing could be attached to the parallel port of an IBM PC and fed 6- or 8-bit PCM sample data to produce audio. Also, many types of professional sound cards take the form of an external FireWire or USB unit, usually for convenience and improved fidelity.
External sound device.s Devices such as the Covox Speech Thing could be attached to. the parallel port of an IBM PC and fed 6- or 8-bit PCM sample data to produce audio Also, many types of professional sound cards take the form of an external FireWire or USB unit, usually for convenienc.e and improved fidelity.