[DllImport("winmm.dll", EntryPoint = "mixerGetNumDevs")]

       private static extern uint MixerGetNumDevs();

           uint numDevs = MixerGetNumDevs();            

static extern uint mixerGetNumDevs ();

Declare Function mixerGetNumDevs Lib "winmm.dll" () As UInt32

  Console.WriteLine("Number of mixers present: {0}", mixerGetNumDevs());

static extern uint mixerGetNumDevs();

Public Declare Function mixerGetNumDevs Lib "winmm.dll" () As Integer

Dim a as integer = mixerGetNumDevs()