Odd Noise from Rear
 

I got into the car this morning and its sounds like a metal elastic band is twanging somewhere inside the rear (right from the front) of the car.

Im guessing its suspension (spring) as it happens when I go around a corner, accelerate or over a bump.

The car is handling well but I cant get under it till later on, so just wondered in the meantime if anyone would know what it is. It does sound like a spring twanging (best word I could use).

Thinking ahead if it is the spring how do I replace it?

Thanks