The appearance of a phantom voice can be traced to the Eastern ritual of the Cuncordo de Castelsardo, a brotherhood on the Island of Sardinia. A choir of four brothers evoke a fifth voice, the quintina. This higher female voice is said to be the spirit of the Holy Virgin Mary.
As Mark van Tongeren recently wrote in his PhD, “At a certain moment my attention was distracted by a female voice that joined the choir. I instantly turned around, because the voice did not come from them, but sounded behind me. Of course there was no woman in sight. Flabbergasted I turned back my head and focused on the four singing brothers. I concluded that this very real voice must have come from them. She arose from the fusion of their four voices. After about 18 years of experience with overtone singing and listening experiments all over the world I thought to have a blind faith in my ears. Until I turned my head in an impulse, and for that moment really believed hearing this female voice and I wanted to see her.”
You can hear an example of the Quintina in the example Te Deum to the right
The quintina is a phantom voice that significantly differs from the above example of overtone singing. In this case, the effect is a coherent female voice, and there is no trace of overtone singing. Vocalist and ethnomusicologist Mark van Tongeren, who witnessed and recorded the ritual, has tried to reproduce the quintina with singers from his vocal ensemble Paraphonia and has travelled to several other similar brotherhoods on Sardinia to find the quintina. But he could never find the phenomena anywhere else, except for this specific place with this brotherhood.
My suspicion is that the appearance of the quintina resides in the very strongly belted vowels of the words sung by the brothers, combined with specific attributes of the acoustics of their church. There is a direct connection between the spoken vowels and particular resonances in the voice that correspond to bands in the overtone scale. A strong emphasis on those vowels while singing could evoke certain higher tones of the voice to become more clearly perceived, under the right acoustical circumstances.
To further explain, Mark van Tongeren demonstrates in the example to the right how vowels correspond to the resonant spectrum of the voice and which overtones are to be found there.