I think that there are ranges of perception.
If the beat frequency is low the two notes are very close together. We hear the beats of the envelope and probably perceive the average of the two notes as the pitch. As someone mentioned this is how we tune our instruments (not just guitar).
If the beat frequency is high the notes are far apart and we likely hear each note separately, not perceiving the beat or the average tone. Humans have a bandwidth for pitch discrimination that is dependent on both the relative different in the tones and the frequency of the average tone.
In short, we cannot easily distinguish two pitches if they are both very low (bass) while we can more easily distinguish them at high pitch (soprano). Hence from a music theory point of view it is not wise to put minor seconds in bass harmony, use large intervals, while small interval harmony works in upper registers. The text Physics and the Sound of Music by Rigden explains this phenomenon quite well.