Well...I kinda hope this isn't the reason, my mums SVE 1.4 was sounding (inside) as if a window was open...or the door seal had gone etc...more when she accelerated.
turned out there was a Massive hole in the middle section of her Exhaust system 
...all sorted now... but...could that be what's happened to yours too?
or it could be a bearing...as Guy said 