So what do you think the howling is then? 
  
If it were a wheel bearing i would hear a change in the noise, a shimmy, a shake, vibration when driving car straight and moving it side to side. 
  
So i ruled that out but the noise is different based on whether I'm accelerating or taking my foot off the gas. 
  
The noise is def. coming from the rear under the passenger seat (its a hatchback).