audiodevinfo not picking up my USB Microphones

I have 3 Samson USB microphones connected via a USB hub to my Macbook Air with the intent of recording 3 simultaneous .wav files into Matlab2013student. However, I'm getting:

>> audiodevinfo 

ans =

       input: [1x1 struct]
      output: [1x1 struct]

>> audiodevinfo (1,0)

and = 

Built-in Microph (Core Audio)

    if true
      % code
    end