This may be caused by faulty equipment or by an incorrect sound setting. Follow these steps:
Use the Volume buttons on the remote control to adjust the volume, or adjust the Volume setting in the Settings menu. See Customizing Projector Features for details.
Make sure A/V Mute is not enabled. (The A/V Mute button may have been pressed.)
Make sure the A/V mute slide (lens cover) is open.
If your presentation includes computer audio, make sure the volume control on your computer is not turned all the way down or muted. In Windows, you may be able to check this by clicking the volume control in your Windows system tray (lower right corner of the screen). On a Mac, you may be able to adjust the volume from your menu bar (top right corner of the screen) or via the volume control function keys.
If you’re using a computer audio cable, make sure it is connected to your computer’s headphone jack or audio out jack. Connect the other end to the projector’s Audio1 port when the computer’s video cable is connected to the Computer1 port. Otherwise, connect the cable to Audio2 if you’re using Computer2 for the computer’s video connection.