Can you hear your turbo bypass?

I could hear it with the factory intake, but had trouble getting the sound to show up on film when we were recording for the Fiesta Movement. The ST I drove in Brazil seemed to have the loudest turbo bypass of any ST I have heard. That one wasn't a production car.

Pssssssshhhhhhhh when you lift off the accelerator. I noticed the sound when in 4th gear about 40mph when the throttle is opened and closed quickly. As soon as the throttle plate closes, you hear the psssssshhhh sound. If you are next to a guard rail, trees, parked cars, or a building with the windows down, it is very noticable. When I went to record the exhaust sound of the Fiesta Movement ST, I followed a route that had nothing near the road to bounce the sound off of, and could not get the bypass valve sound to show up on the video. When I was driving the ST in Brazil, the road was lined with dense trees and the sound could be heard very clearly.

hmmm, so the sound is load dependant. I was thinking the sound symposer tube, but that would make the noise at all times. Can you hear it from outside the car when it drives by?