I'd like to know how supply voltage affects the speed of a DC motor. I'd like a conceptual answer rather than one with mathematical equations. Any research I did only showed answers with mathematical equations.

If I increase the supply voltage, there is very little increase in armature current, and we know that speed is inversely proportional to armature current, so how does supply voltage directly affect speed of a DC motor? 

Edit: An answer that I saw to a similar question said that the voltage difference between the supply voltage and the back emf is dropped across the armature resistance.

Now the above scenario would cause a flow of current through the armature, which produces the magnetic field required for rotation. So stronger the field, faster the rotation. 
But it is known that increase in armature current is a result of reduced speed.


What am I missing here?