I use an app on my phone called Decibel X that measures noise level in dB. A quiet home is in the 40's.

I have a Tech AWD.

Engine started but car not moving -- upper 60's to 70's.
Smooth roads -- 70's to low 80's
Bad roads and highway speeds -- low 90's

FWIW, the quietest cars are in the mid 60's at highway speed, so the RDX is about 1000x louder than those.

 

The guy whose YouTube channel I like measured it at 70.5 dB at 50 mph, rating it at an A- in comparison to other measured vehicles in the same class. That was measured in the Advance model with SH-AWD, so he noted that it has additional acoustic glass.

 

Do you have a link to the video?

 

Cabin noise specifically is at 16:38.

 

BTW, the video is, in general, really good if anyone wants to learn about their car. This was put out shortly after the RDX was made available, so keep that in mind. But he addresses concerns about the "redesign" and whether the RDX is related to a CR-V, he explains why the 3rd generation RDX is faster than the 2nd generation even though there is less HP, he makes comparisons to other cars in the segment, there are numbers on acceleration and braking. It's just a really thorough review of the car and hits all of the points that would interest a buyer. I don't watch his videos any more because I don't intend to buy another car (I'm not a car guy, so I don't find car videos interesting on their own), but his videos were what basically convinced me to get the RDX. So if anyone is on the fence about the RDX or wants to just know more about it, I recommend watching the video. He also has done a few other videos on the RDX, which is not typical for him -- he usually just does one per vehicle -- so those are also on YouTube and are searchable.