Diagnosis
This is coil whine from the projector's power supply or lamp ballast circuitry, often audible in quiet scenes and more pronounced in Bright or Dynamic picture modes.
How to Fix It
Switch the projector to Eco lamp mode. This reduces power to the lamp ballast, which often lessens or eliminates the coil whine.
If That Didn't Work
Try a different picture mode like 'Cinema' or 'ISF Day', which may use a different power regulation pattern than 'Bright'.
Heads Up
While annoying, coil whine is generally not a sign of impending failure—it's an inherent characteristic of some electronic components and varies unit-to-unit.