Oops, I did it again.

While the Houston Chamber Choir was in the midst of rehearsing, I barged right in to get a closer look, or rather a listen, at the repertoire for its upcoming concert "Hear the Future," the choir's 12th Annual Invitational School Choral Festival, to take place 4 p.m. Sunday at South Main Baptist Church. Did we mention it's free?

Singers are typically not bashful and welcome the opportunity to show some hospitality to even the most probing of guests — that would be the video camera.

Some rehearsals tend to be unrefined, but this ensemble means business. But would you expect anything less from a professional group? Artistic Director and founder Robert Simpson reminds me that, indeed, the Houston Chamber Choir is the oldest professional chamber choir in the city.

There is also a very small number of professional chamber choirs in the country, and Houston happens to be home to one. Celebrating its 15th anniversary and themed "A Bridge Across Time," the 2010-2011 season offers audience favorites along with explorative new works, novel ideas and new directions, including a premiere by composer and member Dominick DiOrio.

"Hora Stellatrix" (Hour of Stars) is a movement is from DiOrio's extended cantata-concerto, A Dome of Many-Coloured Glass. Inspired by the words of imagist poet Amy Lowell, the work is ethereal and evocative. Using the marimba as a solo instrument, the composition conjures images of spring, love and nature. The marimba adds a beautiful tint to the ensemble's sound spectrum in somewhat free improvisational form. While being careful not to get in the way of the text, the scoring enhances Lowell's communicative power.

"Hora Stellatrix" from A Dome of Many-Coloured Glass
Text by Amy Lowell (1874-1925)

The stars hang thick in the apple tree,
The south wind smells of the pungent sea,
Gold tulip cups are heavy with dew.
The night's for you, Sweetheart, for you!
Starfire rains from the vaulted blue.

Listen! The dancing of unseen leaves.
A drowsy swallow stirs in the eaves.
Only a maiden is sorrowing.
'Tis night and spring, Sweetheart, and spring!
Starfire lights your heart's blossoming.

In the intimate dark there's never an ear,
Though the tulips stand on tiptoe to hear,
So give; ripe fruit must shrivel or fall.
As you are mine, Sweetheart, give all!
Starfire sparkles, your coronal.

CultureMap's "Art and About", investigating DiOrio's work: