ADLINK IMB-M40H - Manual (Page 28)

16 Hardware Information
USB Connectors
Audio I/O port
The three-jack audio I/O supports Line-In, Line-Out, and Mic-In
functions. The blue Line-In jack connects to an audio source such
as a CD player. The green Line-Out port connects to a speaker or
headphone, while the pink Mic-In jack connects to a microphone.
Pin # Signal Name
1 Vcc
2 USB-
3 USB+
4 GND