Following the apparent dictum that every sliver of American culture must be captured in a feature-length documentary film, Mark Goffman’s Dumbstruck sets to interweaving (always with the damn interweaving) the stories of five people dedicated to the art of ventriloquism. Bracketed by trips to the annual Vent Haven ventriloquism convention in Fort Mitchell, Kentucky, where performers talk craft and hand puppets hang out, the film views the profession through a broad spectrum of experience and talent. Terry Fator puppeteered in obscurity until he took the top prize on America’s Got Talent, knocking David Hasselhoff from his chair by channeling Etta James through stilled lips (he’s now signed to a nine-figure contract at the Mirage in Vegas). Dan Horn is a master hand-manipulator whose plum gig on a luxury cruise liner keeps him at sea for seven months at a time, hastening the demise of his 25-year marriage. Former beauty queen Kim Yeager is torn between finding a husband and fully committing to her dummies, while Wilma Swartz copes with familial abandonment by serving as a quirky aunt to her local and greater performing communities. Finally, shy 13-year-old Dylan Burdette defies his dad’s jock imperatives by dedicating his time to talking dolls. All are compelling subjects, especially the disarmingly gifted and emotionally relatable Horn. But Goffman’s either unwilling or incapable of getting them to move their lips to reveal enough of themselves, or of their artistry, to make the already overly familiar endeavor worth anyone’s time.