Having passed the 80-year mark, Estonian composer Arvo Pärt is entering the tiny pantheon of Designated Great Living Composers - and there's no more unlikely candidate in the 21st century.

Understated, meditative, and full of (hopefully) meaningful silences, Pärt's ascetic music - heard in a trio of high-profile recordings issued late this year - is among the most-played of any composer in the world, and not because mainstream ensembles have embraced it. Rarely will you hear Pärt played by the Philadelphia Orchestra or sung by amateur choral societies. Recordings are the optimum medium here: With audiences present, bits of rustling and coughing can break the sometimes-fragile spell.

Same thing with wrong notes. J.S. Bach is relatively unfazed by them. But because Pärt's music is so pared down, every note needs to be in place - particularly challenging for choruses directed to pause for silence and then pick up where they left off, on pitch.

This is private music, and Pärt is a private author. In his 30-year rise to fame, he has refused to participate in promoting his music, giving him a reclusive reputation that easily translates into a monklike mystique, a holy something-or-other whose musical utterances speak across denominations and nationalities and, perhaps most significant, various levels of faith. So abstract and open-ended are the expressive implications of Pärt's use of sacred texts, lightly framed by Eastern Orthodox religiosity, that he writes sacred music for a secular society. It doesn't ask you to believe. It just radiates in your direction if you wish it to.

For some, it's wallpaper music. Others - like a young street musician I met several years ago in Pärt's native Estonia - can't even discuss Pärt's music without trembling with emotion. But if there's one quality that allows Pärt to cut across so many psychographic lines, it's the music's loneliness. Because he tends not to evangelize, he avoids the certainty heard in so many composers. He touches the fundamental isolation of being alive. At least that's the only theory I have on why hipsters will listen to Pärt meditating on the baptism of St. Augustine.

Seen or heard close up, Pärt doesn't always fit into any tidy, romanticized narrative one might construct from his recent recordings. The real-life Pärt might be seen, back home in Tallinn, out on the Baltic Sea wearing something resembling a baseball cap. He is said to have an apartment adjacent to the conductor Tõnu Kaljuste, whose friends sometimes get mixed up and accidentally barge in on Pärt.

That might seem like barging in on the pope. But Pärt isn't the pope. He's married. He is also a composer who, at one point, had his fill of writing complex music, came back in the mid-1970s with a more economical language, moved to Germany rather than live at home in disgrace under the atheist Soviet regime, and who has enjoyed the devoted patronage of key recording companies, such as ECM and Harmonia Mundi.

In fact, for all his archaic qualities, Pärt is a composer best experienced with clean, unclouded digital sound, and the kind of voices that have come out of the early-music community in the last 20 years. Yet, as the three new discs illustrate, he resists adopting standard musical forms or methods of expression.

On The Deer's Cry (ECM) - featuring incredibly clear, concentrated singing by the Estonian vocal group Vox Clamantis - we hear Pärt composing texts in five languages, in pieces ranging from three to 10 minutes, with subject matter that includes a subtly dramatized scene from the life of Christ titled And One of the Pharisees. The title piece, The Deer's Cry, is seemingly without tangible objective, with incantatory repetitions about Christ with a treble-voice obbligato that develops into the dominating element of the piece. In contrast to Gustav Mahler's cast-of-thousands musicalization of "Veni Creator Spiritus," Pärt's ultra-Zen under-three-minutes setting of that text is so restrained the sound barely displaces enough molecules for it to take its place in the atmosphere.

Pärt has an uncompromising streak. (No doubt with Pärt's blessing, the ECM booklet prints the texts without translations: You get to know it either in the original language or not at all.) And, as much as he refuses to preach in so many of his works, the album Da Pacem Domine (Ondine) features a series of odes and Magnificat antiphons that have big blocks of chords in which Pärt is, undeniably, laying down his laws of faith. Even with the great Latvian Radio Choir under Sigvards Klava, it can sound phlegmatic.

Periodically, Pärt seems to meet the mainstream classical world halfway, and not very successfully. He wrote a Symphony No. 4 in recent years, but, like much of his instrumental work, it fails to imply anything bigger than its ascetic parts. His large-scale Te Deum for three choirs, orchestra, and tape finds his fragile thematic content sounding inflexible and expressively limited.

The best elements of Pärt's world come together in the new Harmonia Mundi disc Kanon Pokajanen (Canon of Repentance) by Cappella Amsterdam conducted by Daniel Reuss. The voices-only 60-minute work sets to music a long hymn, divided into odes, by Saints Andrew of Crete and John Damascene, dating from the 7th and 8th centuries, respectively. Severe and obscure as its components may seem, it's a piece in which the composer puts a welcome personal rhetorical stamp on the text.

Each section draws on a different section of the chorus. Sometimes the vocal writing has its own built-in echo effects, with voices closely trailing one another. Or are those staggered bell sounds? Though I experience diminishing returns on repeated listenings of some Pärt works, this one keeps opening up on further listening, especially in a performance like this, which treats the text and music with nuance. The power of precision is particularly strong in the drone effects he uses that give sections a kind of climatic power.

The simple conclusion is that, like most great composers, Pärt does miss his mark - as suggested by the fact that he revises a fair amount. But because he is a living composer - and his story is not yet over - one doesn't always know which of his pieces are his best or what standards to seek in them. Like most composers, his most famous works, such as the popular Fratres, don't always represent him well.

Arvo Pärt can be a voice in the wilderness who hasn't found a common language with the rest of the world. Or maybe he has been experimenting with nothing important to say. Kanon Pokajamen feels like a culmination of long-simmering elements. Neophytes and skeptics should start there.