"road noise" is mostly caused by two things:
#1 the air moving arround your vehicle.
this is affected by your vehicle's aerodnymics, as well as the way the doors and windows are constructed and sealed. you might have a bad seal arround a door or window if you feel your vehicle is excessivly loud.
#2 the tires contacting the road.
many manufactures opt for a very non agressive, tight tread pattern for oem tires, and usually a 30-40k mile tire. this is done to make that shiny new car as quiet at possible. a more agressive tread pattern, or a harder ruber compound use din a 70-80k mile tire will increase this road noise.
all that said, 100% of vehicles will have higher road noise at high speeds. the faster you go the faster the tires hum on the road, and the faster the wind whistles by your vehicle. so, yes, louder road noise is normal at higher speeds.