Strange whistling sound coming from speaker system of 2007 Volvo V70R, usually following a 'bump' (e.g. pothole) on the road and synced with accelerator

[VolvoDon]

My 2007 Volvo V70R has developed a weird 'whistling' noise; it occurs following hitting a bump on the road but comes from the sound system, not the engine or turbo (directly); it rises in frequency with throttle application. Could the bumping cause microphonic pickup from the turbo or other mechanical component?

[jonesg]

try tapping on the radio to simulate road bump.

Could be  loose connector.