First, you will need to figure out where the sound is coming from. As you drive, have someone in the passenger seat move their head around the front area to see where is the sound coming in the most?
Is the sound equally loud all over? Great – the easy solution below should work.
Is the sound coming from just one spot? There may be a hole in the floorboard – the metal floor – and that would let a LOT of NOISE up through the floor. Have any hole or crack in the floorboard fixed first, or your efforts won’t amount to much. Unless you have an older vehicle, you’re not likely to have a hole in the floorboard. Almost always, the noise you hear is from the floor under your feet not being soundproofed. Most cars don’t do it. High-end vehicles are soundproofed by the manufacturer.
Have you just replaced the tires with new ones? That increased noise dramatically for some vehicles and with some tires – you can use the Easy Technique #1 below, and also wait patiently while your tires wear down a bit over time! Note, the more massive the tires – like for big trucks routing software for truck fleets – the louder they are.
NOTE – Older Vehicles will see the most significant noise reduction (20-50%) from the following procedures. Newer vehicles will also see a nice difference – around 20% less road-noise is reasonable to expect.