In its earliest iterations, the Accord was basically just a four-door, extended-wheelbase version of the Civic. But that "just a stretched Civic" was just right for America, because by 1989, the Accord would become the first import vehicle to become a best-seller in the United States. From then until the ninth -- 2007-to-2012 -- generation, the Accord had undergone a series of evolutions that brought cutting-edge sophistication to everyman's driveway. Most of those innovations served to make the car even better than it was before, but a few might have caused a couple minor issues.
The Accord isn't the first car in Honda's lineup to be accused of having excess road noise; it's not an uncommon complaint on Civics, Pilots and Elements, too. But the reason for that might be exactly the opposite of what you'd think. Over the years, Honda's gotten the art of tuning an engine's intake and exhaust note down to a science. That's a good thing if you like a silent engine, but it does create an odd secondary problem in that the now-silent engine no longer drowns out the everyday road noises that all cars have. In many cases, wind noise would drown out a certain amount of what remained, but the Accord's mileage-enhancing aerodynamics all but eliminate wind rush as well.
Most of those who have sought to reduce the Accord's road noise have found a solution in replacing the car's stock Michelin Pilot HX MXM4 tires. While these tires do offer decent performance on dry roads and a fairly comfortable ride, they're all but useless on ice and snow, only slightly better in the rain, and known noise-makers. As of 2013, Tire Rack's best-selling replacement tire for this car is the Bridgestone Turanza Serenity Plus, which excels everywhere the Michelins are weak, offers even better dry-road performance, and rates an 8.5 in noise comfort compared to the Michelins' 6.5 rating. It's even about $30 cheaper per tire. The Continental PureContact with EcoPlus technology rates about as highly in most categories, rates an even better 8.8 in noise comfort, and it's $10 cheaper than the Bridgestone.
Active Noise Cancellation
The Accord's V-6 engine uses a cylinder shut-down feature to save fuel. Under cruising, the engine shuts down the rear bank of cylinders, making it effectively an inline three-cylinder. Inline-threes are naturally thrashy engines, as anyone with a Geo Metro could tell you. Under light acceleration, it acts as a V-4, which isn't much better. For that reason, the Accord comes with an active noise cancellation system that activates when the engine is in either three- or four-cylinder modes. Using a microphone mounted above the rear window, the ANC system records the sound of the engine, and sends a precisely matched "negative" soundwave out through the car's speakers to cancel out the less pleasant soundwaves from the engine. The thing about noise cancellation is that in a confined space, it doesn't so much "cancel sound out," as it does turn it into less irritating "white noise," or static.
Toggling the ANC
The "road noise" you hear may actually be light static from the ANC system. If you want to find out, you can turn the ANC system off for diagnosis. On your computer display module, hold down the "1-6" and "display" buttons, and then hit the "Power On" button. You'll see the word "DIAG" on the screen. Hit the "1" button to toggle the ANC on or off. It's possible that your ANC might have gotten turned off at some point; in which case, this might be a good time to turn it back on. But if it's already on, try test-driving the car with it turned off and see if the "road noise" you hear goes away. If it does, then the good news is you're just hearing white noise from the ANC. The bad news is that you're now probably deafened by a bunch of racket you've never heard before.
Active Noise Cancellation was part of the plan for the Accord right from the drawing board -- and some say Honda leaned a bit too hard on it to quiet the car, cutting corners on the soundproofing. Those who have turned the ANC off have reported a drastic increase in road noise, seemingly centered around the right-front wheel well. However, the general consensus is that the car as a whole is just lacking in adequate soundproofing mat. At this point, you can buy adhesive-backed sound deadener mat and install it under your carpet, behind your dashboard, on the tops of the wheel arches, on the insides of the metal doors and in the trunk, behind the trunk-to-cabin separator wall. Or, you can just skip all that, turn the ANC back on, buy a set of quieter tires and learn to live with a bit of static in the background.