When you use a HDMI cable that means it will transmit both Video and Sound to the projector. Try setting HDMI as the default Sound Device.
- Right click on the speaker icon on your laptop on the bottom right hand corner and select Playback Devices.
- If you will see HDMI or the Projector name, right click on it and select Set Defaults.
- Click Apply and OK then test it again.
- If you're planning on using the built in speaker of the laptop while connected to the projector.
- Right click on Speaker instead of the HDMI or Projector then select Set as Defaults.
- Click Apply and OK the test it again.