Double Trouble or a Tale of Two Acuras

My wife and I both drive Acura TL’s, 3.2 liter, V6, automatic transmissions. Hers is a '2000 with 105,000miles; mine a 2005 with 130,000miles. More than a year ago, when both engines had about 95,000-100,000miles we started hearing a noise in both cars. It sounds like vibrating sheet metal of a sort, coming from the engine compartment. The sound happens in the range of 35-45+mph and never when accelerating through that range; only when cruising. It started out as an intermittent noise but over time has become louder and happens more often. Both cars exhibit no other problems. Both cars receive routine maintenance and have had no problems. Both are on new tires. Both have had the timing belts replaced when it was recommended.
At first it was an annoyance; now I am concerned that something is coming loose. I am hoping you can pont me in the right direction

That sounds like a heat shield that has either cracked or is coming loose. It won’t hurt anything but it is annoying.

Concur. They can usually just be ripped off when they get loose like that, unless you park in dry tall weeds (i.e state fair, etc). Otherwise you can usually have a muffler shop weld a new one on for not very much money.

Yes I agree also. Look into it. Open the hood and see if there are any heat shields over your exhaust manifolds…see if they are loose. Grab a broom stick and lie down next to the car and tap all alond the entire exhaust system…you may find it rather quickly this way. Let us know

Do You Know The Sound Associated With Pre-Ignition ?

Do you use regular, mid, or premium grade gasoline ? Looking at the Owner’s Manuals and/or fuel fill area for a placard, is a certain octane rated gasoline “required” or “recommended” ?

If you don’t know that sound and you’re not using a high octane rated gasoline then next time the tank(s) get low, fill with the higher octane gasoline and give that a try.

"More than a year ago, when both engines had about 95,000-100,000miles we started hearing a noise in both cars."
Over the miles you both could have picked up a little carbon in the engines’ combustion chambers which would explain it starting at about the same mileage.