“Flock” will present a special reconvening of The Readers Chorus, led by Sara Roberts, for the first time in several years. Formed to utter into the world all manners of language as sound, the chorus will perform Black/White Oratorio by Robert Lax & John Beer, entirely composed of names of colors, for Dog Star 20. As with language, Mason Moy begins the evening with bringing together a vocabulary of pitches through his new composition for string trio.