Ambient sound describes the background sounds in a scene that make things feel more real to users wearing the virtual reality device. You can turn the ambient sound up or down using the Ambiance Audio Controls.
Click on the “Sound Wave” in the Audio Control Panel.(A character stands in a lobby; a "Sound Wave" icon in the lower right is circled)
Use the slider to adjust the volume of ambient sound in the scene.(A character stands in a lobby; an "Audio" pop-up in the lower right displays a slider bar labeled "Ambiance")
Close the panel by clicking the X button.