I have a 1996 Contour SE, and i have the same exact problem as you. Going straight it makes a humming noise, turning right it disappears, and turning left it is louder. I recently took my car in to the Ford dealer for overheating problems hoping it was a recall and i could get it for free, but no, it was those plastic fins on the water pump, which in time killed my thermostat too. $399. what a ripoff. but anyway, they told me that the noise was in fact the wheel bearings.
