Nick, if I once got the G right I could find my way by relative intervals to the Eb (major third down) and anywhere else the same way. Some intervals are too hard for me to hear, but I can composite them from two easier ones. Now I will become less sure about it as the minutes go on, especially if there are auditory distractions. Certainly if someone lies to me ("this is a C -- snicker snicker") I may lose my place.
-Glenn