The distinguishing feature of almost all vocal music is the inclusion of spoken language. Poetry and music combine to create a hybrid form that is more than the sum of its parts. The relationship between the two art forms and the incorporation of a poet’s voice into the melody and harmony of music is the focus of the musical preparation for the choral concert this Friday. The concert, entitled “The Poet’s Voice,” will include all three large vocal ensembles: Chorale, Women’s Choir and Concert Choir. The Chorale program will feature pieces by Barber and Dello Joio, with the able accompaniment artistry of Mandy Gessler. The program will start off with a piece by Heinrich Schutz that will feature Stephen Spears, one of the vocal professors on the conservatory faculty. The Women’s Choir program consists of two multiple-movement pieces. The text of the first piece, “Choral Hymns,” is from the Rig-Veda by Gustav Holst. It is a translation from the original Hindu texts originally written in Sanskrit, the holy language of ancient India. Holst, unsatisfied with other translations of the Rig-Veda, essentially created his own translations, which he then set for the piece. The other selection, “My Girls” by Gwyneth Walker, is an old favorite of the ensemble’s director, Philip Swan. Richard Bjella, director for both Chorale and Concert Choir, has a few tricks up his sleeve, as usual. The Concert Choir will first perform three pieces that, according to Bjella, are tied together by “a dark, tranquil nature.” The pieces by Brahms, Stanford and Badings, are representative of German, English and French poetry respectively. The piece by Stanford, “The Blue Bird,” will give soloists Sarah Berendt, Caitlin Cisler and Jeni Houser a chance to display their talents in a solo context. Finally, Concert Choir will perform a relatively new work by Eric Whitacre, “Leonardo Dreams of his Flying Machine.” With text by Charles Silvestri, this work had its premiere less than two years ago and is already widely performed around the United States. Bjella agrees with many of his students, who think that this is probably the most difficult choral work Whitacre has produced to date. It makes its way through very disparate styles and seven or eight keys in a very short span of time. “It’s everything in nine minutes,” says Bjella. This “everything” includes numerous solo opportunities for singers like Deanna Wanner, Alisa Jordheim, Beth Summers-Minette, Laura Muller and Spencer Dorn. The concert is at 8 p.m. on Friday, Feb. 25, in the Chapel, and is free and open to the public.