When the microwave we had been using for several years failed recently, a family member passed on to us an LG MS2596OW microwave to use. The microwave is fine except for the mind-flippingly irritating electronic tune that it constantly plays when cooking finishes. The user manual provides no assistance in disabling the sound, but thanks to a suggestion from a review site, I learned that it is possible to mute the sound on this microwave by holding the Clear and Keep Warm buttons for 5 seconds. Peace at last!
You can repeat the procedure to turn the sound back on again, but the only reason you’d want to do that is to demonstrate how annoying the sound is when a visitor asks why the microwave doesn’t beep.
Note that if the power to the microwave is disconnected, the mute setting doesn’t stick, so you have to mute it again when the power is reconnected.