2015 4 cylinder make buzzing noise at 1750 rpm

This noise sounds a little like a turning on hair clippers but also reminds me of a heat shield rattling against exhaust parts. In 4th gear at 50 mph/1750rpm it starts and then stops completely at about 53 mph. There is no vibration that I can feel. In 3rd gear it does the same but not as loud at 1750rpm. Occasionally I hear it in 1st and 2nd gear. If I blow through 50mph at full acceleration, no noise. It does not sound off unless I am moving on the road. I can not duplicate it sitting still. I have checked all the shields up to the exhaust manifold but find nothing loose. I don't think it is in the cab but have pushed on about everything I can reach.

What do you think?

Thanks

 

Check out my post here: https://www.tacomaworld.com/threads/weird-rattling-in-engine-bay.734449/#post-26154752
Not sure if this occurs on a 4 cyl but the buzzing/rattling I heard was similar to yours.