And then, barely noticeable—an indefinite pitch lower, another hum "ohh" follows, moving forwards in time in parallel motion with the first hum. Seconds later a third "aaa", even lower than the "ohhh" enters, joining the first two vocalisations in close-harmonic following of lines—although harmony would be less than an ideal word for the ensuing shimmering sonic texture. At this point in time our ears are still cocked; we were relishing the quietness of it all.

But the two singers to start the first utterance, huddled in an inward-facing circle of twelve or so others, begin another ‘eee’ at a higher pitch as the rest of the small choir maintain their last notes, only to consecutively break and join with subsequent "ohhs" and "aaas". Thus a cascade of sound is slowly built up, step by step, in ascending pitch and volume.

The song circle sustains and pushes towards a slow climax of a vibrant aural halo, wrapping itself around the ears of all present in the performance space.

Welcome to the pasibutbut—or a millet-growing song ceremony, traditionally performed at the start of spring in open rice fields by the Bunun people of Taiwan.

As one might imagine, the creeping sonic crescendo makes symbolic representation and ritual encouragement of rice seedlings sprouting and reaching towards the sun.

The singers we hear today have in times past been (and by and large, are also presently) the guardians of these fields; farmers willing their crops to grow, flourish and yield a good harvest.

Strikingly, the Chorus makes claims of presenting "authentic" performances of indigeneity and Bunun life. Increasingly, however, the term "authentic performance" itself has come to be contested.

This is because the ways of life of indigenous peoples in Taiwan have been morphing steadily through history, and have ever more so been changing in the wake of not only global and domestic developments in industrialisation, but also rapid technologisation. Recent transformations in the digital media world have also led to the steady recalibration of indigenous livelihoods, lifestyles and culture production.

Even the once-innocent term of "mountain" in the very name of this vocal ensemble has become contested territory as political-correct terminology on how to label the first pre-Han settlers in Taiwan has changed.

Today the state-endorsed and self-identifying label is "indigenous". To an extent this term is replacing that of "aboriginal" of the more recent past and, earlier, the negatively-connotated "mountain peoples" and "barbarian tribes" (in translation from the Japanese banzoku when Taiwan was a colony from 1895 – 1945).

To be sure—the mountain villages resided in by indigenous peoples still exist in Taiwan, if many remain largely populated by ageing folk. Many indigenous peoples actively leave ancestral residences to seek jobs, education and cosmopolite lifestyles in Taiwan’s cities. Still, they return for annual harvest festivals, weddings, birthdays and funerals, re-asserting their indigenous identities in too-short, concentrated bursts of communal "traditional" and ritual activity.

In the so-called "mountain villages" themselves—Japanese round-grained rice has replaced millet farming with hunting restricted to seasonal and state-licensed stints in carefully delineated territories, even as Facebook and fully-flushing toilets in airconditioned ‘traditional’ homes with beautifully-tiled "outhouses" are par for the course.

So—where does the "authenticity" lie in these changing times? An alternative word—memory—might be a useful stand-in for many indigenous groups.

As with many minority groups around the world, indigenous peoples in Taiwan often end up showcasing their potentially exoticised rituals on tourist stages, and find themselves delving into the performing arts for economic sustenance and, more crucially, reclaiming of the past for themselves in new ways and new identities.

In the case of the Bunun Mountain Traditional Chorus, the ‘authentic’ songs are not so much ‘authentic’ to a lost time, than "authentic" to the group’s current balancing act of keeping alive, in contemporary and sustainable ways, vocal genres whose contexts of existence have since been lost.

For one, the intervention of the church—seen in musical and educational encouragement of the chorus’ community advisor of pastor Vilion Lee—has already substantially reframed "tradition" for better or worse.

This has been achieved through the incorporation of new theologies into Bunun pre-colonial cosmologies enacted in rituals and songs, in parallel with the introduction of new song texts and performing styles.

And the Bunun are not the only group in Han-dominated Taiwan to have actively embraced Christianity. Many other sister groups from the Amis to the Paiwan have converted to Catholicism, in acts of both political rebalancing in the face of Tao-Buddhist dominance, and in allowing the church to platform its proselytising efforts through community-building and education campaigns.

Indeed, this researcher’s own experiences with Amis singers in Taitung have revealed the church to complement indigenous needs through the documentation and preservation of orally-passed down songs in the transformed cipher notation of hymnals.

The church has also provided stable platforms and new contexts for community music groups to congregate, sing and rehearse.

Elsewhere, other indigenous song groups in Taiwan have embraced karaoke, cultural troupes in aboriginal theme parks, stage performances and pop music as parallel creative outlets for the diversified sustaining of their song cultures.

In the case of tourist park musicians, this can sometimes be a financial balancing act, as this researcher’s own interviews with such figures have shown: the stability of a day job selling souped-up and exoticised "inauthentic" fare to tourists paradoxically allows singers to retain a different kind of professional existence in their livelihoods as singers, and maintain their own dying vocal traditions for themselves in parallel, otherwise economically unsustainable zones.

But made-for-tourist performances of indigenous music are not the only showcases. In the examples of media-friendly, hip and technologised pop artists such as Amis singer Suming and Bunun performer Biung, pop music careers feed into new waves of Taiwan aboriginal nationalism and wider transnational social activist movements carried out on behalf of indigenous communities.