SPBGetDeviceInfo
long inRefNum; a valid reference number for a sound input device
OSType infoType; information type Ptr infoData; a pointer to the appropriate data device specified by the inRefNum parameter.
inRefNum a valid reference number for a sound input device
infoType type of information you desire is specified in the infoType
parameter.
infoData is an address to the appropriate data.
noErr (0) No error
siBadSoundInDevice (-221) Invalid sound input device
siUnknownInfoType (-231) Unknown type of information