Dear Tom and Ray:

My youngest son has been diagnosed with autism. One of the problems that can be faced by autistic people is an oversensitivity to sound. Certain sounds can be very painful to them. Well, while we were on our way home from Grandma's house in our old van -- a bare-bones 2000 Plymouth Voyager -- the little guy started to scream. It took us a while to figure out that his discomfort became greater with vehicle speed, and worsened when we drove on rain grooves. We just purchased a 2003 Dodge Grand Caravan that is pretty decked-out and much quieter. However, I want to get the new van as quiet as possible on our modest budget. We live in Arizona, where rust isn't an issue, but I'm wondering if undercoating would quiet the van any more? -- Ken

TOM: Geez, what a tough situation, Ken.

RAY: I don't think undercoating is going to do much in this situation. What really makes a difference in interior noise is 1) how well a car is put together, and b) how much sound-deadening insulation has been stuffed into every crack and crevice during the manufacturing process.

TOM: I'm sure the 2003 Caravan is a lot better than the 2000, because if nothing else, it's newer and has fewer rattles, squeaks and vibrations coming up from the road.

RAY: But if you're looking for the simplest, most effective way to get a quieter ride, I would say that tires would top my list.

TOM: These days, most cars have all-season tires. And most of those tires represent a compromise among ride, handling, tread life and traction. But since you live in Arizona, wet weather and snow are probably not concerns for you. So, you can afford to emphasize noise reduction in your tire search and look for a nice, soft, quiet tire.

RAY: The Web site www.tirerack.com has a very useful survey of tire users. You can check its "survey results" to see how your current tires rate for noise. If there's room for improvement, you can use its "tire selector" process, select "noise/comfort" as your No. 1 priority, and see which quieter tires fit your Caravan. Then check "survey results" again and pick the best of those.

TOM: Another option is that both Bose and Sony have come out with noise-canceling headphones. They're designed for people to use on airplanes and places where continual noise leads to fatigue. They work very well. I don't know if you could get your son to wear them (or if he's really bothered more by vibration than by noise), but these headphones really work, and they might help.

RAY: And then, when it's time to shop for another car, I'd suggest that you look at the luxury cars that are known for their sound-deadening environments. Cars like the Lincoln Town Car and the Lexus LS 430 are certainly available on the used-car market. If those are too expensive, you might try a Toyota Avalon or Lexus ES 330. You'll have to take the little guy with you on test drives to see what his actual response is, but you'll probably do better if you start out with some of the quietest passenger compartments on the road. Good luck, Ken.