Is it the Honda hybrid sound? I owned two hybrid CR-Vs (loved those cars, but got into an accident one year ago today that totaled a three month-old CR-V hybrid and car prices went up so fast we had to downgrade). We always called it "Hell Choir". It makes for an amusing contrast to the horn, which sounds like a clown car.

https://youtu.be/K_7Hd3M2qrc