Earlier quoted context omitted.
I agree. I can tune a guitar to within a half a semitone of accuracy without reference just from knowing how the open strings are supposed to sound after 20 years of playing.
> knowing how the open strings are supposed to sound well that's the whole question isn't it? If you know how an open string is supposed to have, that's what people call absolute pitch?
I know the Super Mario Bros. theme starts on an E, so I can identify an unknown pitch by recalling that theme and comparing using relative pitch. But that's quite a slow and unintuitive process, and it's easy to make a mistake. People with absolute pitch just hear the pitch without having to "recall" a reference note to compare to like that.