No I mean I can put on a new set of strings, hit the low E and tune it to what it is supposed to be without listening to a reference tone at the same time. I can hear the note in my head. That's my reference. It's like listening to a phone's dial tone. Everyone knows what that sounds like. Just imagine that note in your head and tune the string to that until it sounds right to you. I can do that with all the open strings.
Team Nachos