Documentaries about film technology, at least those that aspire to reach some portion of a mainstream audience, have to make wonkiness ingratiating. “Making Waves: The Art of Cinematic Sound,” a cogent and winning picture directed by Midge Costin , does this in a variety of ways.

After a pro forma but not overly pedantic verbal explanation of why sound matters to movies, it hits us with vivid examples, not just from contemporary films boasting big-bang multichannel audio effects, but relative chestnuts such as 1931’s “Dracula,” which, we are reminded, still packs considerable scary-noises mojo.

The movie then rolls out the talking heads. Directors, including Peter Weir, David Lynch and Steven Spielberg, have their say, as do a lot of sound engineers, editors, effects creators and more. They’re a diverse and chatty bunch, and they reveal a lot about both the overt and almost subliminal ways in which sound can take hold of our emotions while we’re watching a film.