Another a cappella opera

The Wall Street Journal reviews an a cappella opera premiered by Opera Memphis and Playhouse on the Square, which has a sort of pit-orchestra consisting of singers, for which they use the Bobby McFerrin-invented word “voicestra”:

[Michael] Ching’s remarkably inventive opera is a celebration of what voices can do and still, with the exception of a few startling vocal percussion effects, sound like voices. The voicestra —between 15 and 20 amplified voices, depending on the performance—supports the singers on the stage, its overlapping lines and syllables weaving around them, amplifying their characters and conflicts, sometimes echoing their words (or even their thoughts), or supplying atmosphere. The voicestra gives the opera an added human dimension, and its invisibility goes with the magical nature of the story.