[bkanber]

I also want to add, since this is more of a deep auto-industry thing, that NVH testing is almost like longitudinal health studies. NVH engineers actually have charts of which specific frequencies our internal organs resonate at. For a layperson it's easy to imagine that NVH testing is just a matter of setting up a dB meter and some accelerometers to make sure things aren't bouncing around too much, but it's actually much more nuanced than that, and the engineers have to consider the long-term effects of driving in the vehicle.

One easy way to picture this is: recall your last long road trip, or airplane flight, anything more than 3 hours or so. You get so tired after those, especially considering that you've only just sat still for a few hours. But in actuality your body is making hundreds of tiny corrections to posture each minute, in response to the vibrations of the vehicle, and that literally exhausts your muscles and nervous system. Now imagine that you make that car "5% more harsh" and redo the road trip; you will feel the compound effects of that additional harshness. Auto manufacturers take NVH very seriously, because it turns out to be a pretty big deal.

My point is that even if NVH comes back OK in the lab, they still will need a good deal of real world data with test subjects representative of the 'average driver' before they can make a determination.

Edit to add: I know of at least one case where the entire drivetrain of a vehicle was redesigned due to NVH.

[throwaway0a5e]

And this stuff is exactly why it's a million times less fatiguing to drive a vehicle from 2020 over one from 1990, even if you control for almost every other variable by picking one that has changed minimally (i.e. a few panel vans and many medium duty trucks)

[ycombigator]

That's a wild over exaggeration.

[Firehawke]

That certainly puts an interesting spin on the one time I had to ride the back of a bus from west coast to east coast. It was three days and I was physically and mentally exhausted at the end despite sleeping for a fair chunk of it.

Edit to add: Thanks for your input on this, it's insightful and interesting!

[chris_st]

A friend recommended I wear earplugs on plane flights, for a similar reason. He said that the constant noise stresses our bodies/minds, and lowering it makes the time more pleasant. It may entirely be placebo effect, but I find it very helpful.

[ElijahLynn]

Thanks for this. Is there a way to look up NVH values for current tires? I'm assuming some have better NVH values than others and they could have an effect on making the drive feel nicer.

[YossarianFrPrez]

This was very cool to read; thanks for such an informative comment.

I imagine this will sound naive, but I wonder why this sort of vibration can't be addressed with shock absorbers in the seats?

[bkanber]

> I wonder why this sort of vibration can't be addressed with shock absorbers in the seats?

Not at all naive, because it is addressed with shock absorbers in the seats; that is one of the very many tools NVH engineers use. :) But they're not 'shock absorbers' in the way you're thinking; the actual foams used in the car seats are specifically designed and selected to dampen certain frequencies. But, kind of like a speaker or headphones or even ear plugs, the dampening happens over a spectrum, and in general our organs resonate at lower frequencies, which are harder for foamlike materials to dampen.

NVH engineers view the entire road-vehicle-driver system as a huge, complex, spring-mass-damper system, and do a whole ton of partial differential equations to solve for the outputs.

Edit to add: so why not use traditional 'shock absorbers', the spring-damper kind that you're used to seeing? For passenger vehicles the answer is weight and complexity. But many trucks and tractors and so on do in fact have these.

[YossarianFrPrez]

Fascinating, thanks for the response.