I have recently noticed deep woooooo! Sound, I.

I have recently noticed deep woooooo! Sound, I thought is coming from the driver side of the front tyre and as if emanating from this side of the car hood. This is reinforced by the fact that anybody sitting at the passaenger side do not hear this sound as much as I do on the driver seat. Ther on, I decided it was the hub or bearing of the drivers side leg and I changed the hub. Problem is that the sound is still coming on and am advised to also change the passenger side hub. I am confused, the sound is loud and more pronounced especially when on high speed but when driving at low speed, I hardly hear it. Please help and advise.