Why is the sound of a car in reverse gear so distinct?

Question

you can tell a car is in reverse from the sound without actually seeing it

Answer 1

its the gear ratio, its smaller, so it windes up.

Answer 2

Since reverse gear isn't used as much the manufacturers don't shape the gears for optimum noise suppression.  This is because it is cheaper.  Straight cut gears are cheaper to make and a tiny bit more efficient but they are noisy.  Helical cut gears are really quiet but are harder to machine.  Why waste money on a gear that is only used for 0.09% percent of the total driving?

Answer 3

cus it not going forward