If I test drove my brand new M3LR and heard this noise during that drive, I would've declined delivery. Instead, I accepted delivery, heard this noise on my way home and have been dealing with it ever since (in cold weather). As friends all have Tesla vehicles as well (2x M3, 1x MY and 1x MS), I know (and they confirmed, except the Model S owner, because like you, he can't hear the noise either) the noise mine is emitting is not a noise they have ever heard/they too would be upset if their Tesla (new or not) was making it.
Not to be rude, but you can't hear the noise (great, good for you), so why are you commenting on this thread as if you can/you've determined it is a normal noise (it isn't) and shouldn't upset owners who can hear it? You can't hear it, your opinion is therefore contributing nothing because you have no frame of reference. Those who can hear it do not think it is normal, at all, and this group of folks includes Tesla technicians. I think Tesla technicians know a bit more than you do about the "normal" or "expected" noises that these cars can make.