you connected external speakers to the projector, you can connect
your computer to the projector with an audio cable to play
Connect one end of a 3.5 mm stereo mini-jack
audio to your laptop's headphone or audio-out jack, or your
desktop's speaker or audio-out port.
Connect the other end to the Audio port that corresponds to the
Computer or BNC port you are using. If you are projecting
video through the projector's DVI-D port, connect the end of your audio
cable to the Audio3 port.