Humming noise

[AMAC1]

Humming noise

Hi all, I have a CLS 350 (2013) which has developed an annoying humming sound when doing speeds above 40mph. Initially thought it was a bearing going bad but had it checked out with no play in the wheels. Had tracking done and new tyres fitted but no difference still the same noise. Difficult to determine which side it is coming from. It is almost as thought it is somewhere in the middle. Steering is all good too. Trying to think out of the box! I would say however the sound has progressively gotten louder over several months. Still thinking it’s a bearing? Any thoughts would be greatly appreciated

 

[Bellow]

Does the frequency/pitch of the sound vary with speed (once beyond 40mph)?

I've had wheel bearings go bad and show no play despite noise - which appears at a certain speed. Roughness rather than play may be the giveaway in time. Don't be surprised if it gets very noisy briefly. At that point roughness or play will be detectable. Unless the answer to my question is that the frequency does vary, I'll wager it is a wheel bearing.