Per your request, I am emailing you about barbershop tuning / methods to teach it. Obviously, we use the just intonation system. We feel the chords have a much better chance of creating the overtone and undertone series when tuned justly. We teach “horizontal tuning”…that is, tuning to the key center, and we teach “vertical tuning”…that is, tuning the harmonies to the melody. In our style, it is vital the melody stays true to the tonal center (horizontal), and the harmonies stay true to the melody (vertical).
As barbershop uses a large percentage of dominant 7th chords, one of the most important things we teach is that the root must be tuned to the tonal center, the 5th scale degree must be tuned on the high side, and the 3rd and minor 7th must be tuned on the low side (in comparison to equal temperament). This method becomes somewhat tricky when singing through the circle of 5ths are what was once your 5th scale degree (tuned higher), is now the root of the new key, so constant adjustments must be made.
We also place significant emphasis on matching vowels perfectly within the ensemble. We have many exercises (like the ones attached), built around the circle of fifths, in which we incorporate many different vowel sounds. This allows the singer to learn how to tune each interval and tune to the tonal center, all the while concentrating on matching the vowels of his fellow singers. Barbershop vowels are obviously much more vernacular and casual than those sung English vowels in choral music, but the concept is still the same.
Vocal resonance and placement are key to tuning for us as well. Barbershop ensembles strive to match each other as well as possible (I dislike the word ‘blend’!) from a placement standpoint. If the lead singer has a natural, forward, bright placement, the rest of the ensemble makes every effort to match that same resonance. If the lead singer naturally sings with an open, full, rich, resonant natural tone…the other singers have a job to follow suit.
Finally…you will rarely, if ever, see a piano in any of our rehearsals. We utilize justly tuned learning tracks to teach to the majority of our amateur singers, so they can get the full understanding and aural memory engrained in their brains.
We attempt to do all of these things by teaching proper vocal technique, breath support / management, posture and alignment, and free / relaxed / effortless singing. It is quite the challenge, but once a ‘barbershopper’ hears that perfectly tuned chord and executes it a few times, he usually is able to repeat it over and over again, and is very eager to do so! There is nothing quite like singing with three other people, but sounding like 5+ people!