Or a variation in the aggregate. Or perhaps different weather requires a variation in the aggregate or causes the macadam to compress differently under the rollers. I’ll bet a paver would know. If I run into one I’ll ask.
I suspect the pitch change is the stripper wheel speed vs the speed of travel of the vehicle itself creating a pattern that varies slightly. The change in pitch was occurring within seconds, then steady for a while, that abrupt change for a few more seconds.
I remember reading about an artist who wanted to add texture to a road in such a way it would play a song as you drove over it.
@circuitsmith there is a road that is “musical” near where I live, gets your attention if you don’t know it’s there.
As to the original question a front wheel drive bearing may not have any play and still be bad. The best way to check is to have the vehicle in the air and run the car up to speed and listen to the bearings with a stethoscope.
I have a stretch of musical road also, my future invention, like a needle in a record groove, pavement surfacing could be made to replicate a voice, stop ahead etc.
“The best way to check is to have the vehicle in the air and run the car up to speed and listen to the bearings with a stethoscope.”
Personally, I think it’s more accurate to hook up chassis ears and drive the car. That way, everything is real-life conditions. By switching channels, you can quickly determine which corner is making the noise. It’s time consuming, but if you want to be sure . . .
I’ve had many vehicles racked, and they usually didn’t make whatever drivetrain noise I was trying to find, because the components were not “loaded”
But racking the car and using chassis ears is great for finding an engine and/or accessory noise, such as a noisy alternator, water pump, etc.