Sensuous simpering sighs and volcanoes of vowels fascinated the audience in Brendle Recital Hall on the Wake Forest University campus as Roomful of Teeth, a Grammy-winning a cappella octet of singers, filled the hall with stunningly precise and well-tuned singing of a type rarely heard. From the pristine beauty of the 2013 Pulitzer Prize-winning Partita for 8 Voices by North Carolina native Caroline Shaw to the raw and raucous yodeling of soprano Esteli Gomez in Rinde Eckert‘s “Cesca’s View,” the evening was full of delightful surprises. Text and words seemed to be incidental to sounds, often pure but sometimes nasal and raspy. Pitches often wafted and waned seemingly, without rhythm, but at other times crisp repeated Ks and Ps and Ts laid rhythmic expectations as insistently as the snare drum in Ravel’s “Boléro.” Indeed, the whole concert was an intriguing study in phonemic awareness.

Shaw’s Partita occupied the entire first half of the concert; it is composed of four movements of vastly contrasting characters and moods. The opening Allemande could be a square dance, with the caller naming the moves and everybody responding in quick rhythms that give way to chords that sway smoothly and evenly on and off pitch and back again. The sensuous Sarabande which follows starts with three ladies humming and briefly dipping their pitch like a sigh, to open on a clear “Aaaah.” The clarity of the “Aaaah” contrasts sharply with the later nasal and edgy “Âââââ” (rhymes with “baaad” with a twang) which the octet sang with gusto and glint in the eyes.

The subsequent Courante “Ahs” and “Ehs” itself into a cheerful and lilting 5/16 or 5/8 that sort of chugs along until interrupted by a gorgeous bass chord from the gentlemen of the octet. A long hymn-like section of pure vowels, devoutly sung by the ladies, repeats itself at length before giving way to sliding parallel chords (fifths be damned!). The closing Passacaglia uses words for their rhythmic value rather than for meaning when suddenly the babble is interrupted and the listener endures several pregnant seconds of silence before being again tucked under the blanket of babble. The “Âââââ” begins insistently again, followed by various sounds made with a curled tongue, some didgeridoo-like “Errrrs” and “Urrrrs” with all the harmonics that pursing and opening lips can make.

The audience was full of intrigued questions and fascinated wonder during the intermission. Here were things sophisticated concert-goers had never heard, performed so well, so cleanly, and with such astonishing precision.

The printed program was ignored for the second half of the concert, which included single works by five different composers, each notably different from the other. First was the longer “Render” by music director Brad Wells, who never appeared on stage. For this evening’s performance, Randall squires, audio engineer with Nomad Sound, manned the sound board. .“Render” has a hypnotic slow “Nu, nu, nu, nu” introduction which repeats itself while wordless iterations and reiterations of slowly sung vowels move the mind.

“Among the Minotaurs” by William Brittelle was the first work of the evening to actually use words for their intrinsic meanings – although the poetry they intoned was absurd but full of colorful images like “purple tree,” “poisonous mango,” and “Bear Bryant,” the legendary football coach who is loosely the inspiration for the poem by the composer. Alto Virginia Warnkin was the lucky singer with the lion’s share of the words and action.

The third work in this half, “Suonare” (“to sound” or “to play” in Italian), was composed by the octet’s tenor, Eric Dudley, and pits six members (singing in English) against the two sopranos, Gomez and Eliza Bagg, who sang the same words in Italian, in canon at the unison, but with gorgeous high operatic voices with beautiful vibratos.

“Cesca’s View” by Eckhart gave Gomez the chance to show off her spectacular ability to yodel in the quartet for four females. The concert ended with a spirited performance of “Quizassa” by Merrill Garbus of tUnE-yArDs fame which pointed yet in another direction that Roomful of Teeth might also go. The versatility of style, techniques and repertory of the octet was extraordinary – and the audience was quick to show its approval of this fascinating and polished group of singers with a standing ovation.

Adults of my generation remember the Swingle Singers, formed in 1962, and their jazzy fascination with J. S. Bach. In 1969 came the mixed a cappella quartet, The Manhattan Transfer with its jazzy versions of pops and fusion and in 1980 Take 6 started its meteoric rise, incorporating clicks and “lip trumpet and trombone” to impersonate a rhythm section and brass players. Founded in 2009 by Wells, Roomful of Teeth has recently put on the mantle created for the Swingle Singers in 1969 by performing Luciano Berio’s Sinfonia, a gigantic work based on Mahler’s Second Symphony but which incorporates the human voice in novel and unconventional ways.

Roomful of Teeth performs a different program Saturday night at Duke University. See the sidebar for details.

Note: As it happens, the Swingles were in Raleigh earlier in the week. Click here for a review. And click here to preview (or revisit) Shaw’s Partita.