My 2.0 diesel has laminated glass all round, any noise heard inside the cabin is wind/tyre noise and would be just the same if it ran on batteries, can’t see how a background sound (never really hear any as I have music playing gently most of the time anyway) would make any difference to stress levels.
I suspect these people asked in the survey were trying to promote the fact they feel better about driving electric and giving positive answers will make better reading for the green agenda.