Side sensors sensitive to sound?

[Blup85]

Drove 500miles + yesterday down I5 on our Ap1 P85+.
Noticed something odd when I passed a vehicle that was making a terrible squeaking/grinding noise which sounded like a bearing was fried. Once I came directly adjacent to the noisy vehicle, my ap1 display started showing red on the proximity center screen and AP shifted me way over to the left side of the lane like it was trying to avoid hitting a car, even though we were both centered up pretty normally.
I'm guessing the noise caused the confusion, but why (asking the bigger nerds here)?

 

[Ande]

Of course, they are sensitive to sound. Those are ultrasound sensors (and emitters) sending series of pulses and listening for feedback.

 

[Brettski]

Of course, they are sensitive to sound. Those are ultrasound sensors (and emitters) sending series of pulses and listening for feedback.

I sense that a Physics dissertation will be posted very soon

 

[scottm]

It's possible to confuse these sensors with sound emissions of your choosing, like this: get near the sound frequency of interest (~60 kHz +/- 10 kHz) and get it loud enough (beyond 100dB @ 3 meters) ... don't even have to be modulated or bursted or encoded in any way ... just flood the field with loud* sound and you're car is "blind" on those sensors.

*People only hear up to ~15 kHz so you'd not notice these sounds if they were happening. But it would drive a bat nuts.