Humans have five senses, whereas cinema is limited to just two, sight and sound. We often hear how movies are a visual medium, but what about the other, invisible half? Filmmaker Sam Green (“The Weather Underground”) wants to get audiences thinking with their ears as much as their eyes, constructing an immersive, audio-driven essay film that focuses our attention on sound: how it works, what it can do and the way that specific noises can either unlock memories or spark entirely new ones.

Full to bursting with humor, emotion and curiosity, “32 Sounds” is a uniquely mind-expanding plunge into a dimension of the human experience so many of us take for granted, a rare and rewarding sonic journey with the potential to enrich our lives. “Enrich our lives?!” I can practically hear you asking. If that sounds like too grandiose a goal, consider this: Unless you’re a musician, an audio engineer or an otolaryngologist (ears, nose and throat doctor), chances are, you don’t spend much of your time reflecting on the miracle of sound. But you’ll almost certainly come to appreciate it differently after seeing … er, hearing “32 Sounds,” meticulously constructed as it is to pair relevant, enlightening visuals with a philosophical inquiry into all things audio.

Green designed this active-listening project to be experienced in any number of ways: Ideally, you’ll catch a live show, like the one I attended on the rooftop of the Montalbán in Los Angeles during the 2022 Sundance Film Festival (“32 Sounds” was the highlight of the New Frontier section). For such performances, Green appears in person to narrate the screening — which feels more like a polite, sit-down concert — while composer JD Samson supplies the score. More likely, you will catch it on streaming, where a slightly different cut attempts to re-create the intimacy of Green’s in-person delivery. (It is this version that SXSW programmed on opening night at its largest venue, Austin’s Paramount Theatre, as Green was unavailable to emcee.)

No matter the format, it’s important to experience “32 Sounds” with noise-canceling headphones (which are provided at live gigs), as the movie is mixed in such a way that the direction the sound comes from is practically as important as the audio itself — plus, it helps to cut out the rustling, coughing and miscellaneous din that so easily distracts in group settings, like film festival screenings. By insisting on headphones, Green has redesigned the collective dynamic of seeing a movie with strangers such that the hearing part feels private, not unlike dancing at a silent disco — speaking of which, all shows include an intermission, at which point Green invites audiences to stand up, take off their headphones and dance.

Green designed “32 Sounds” as a participatory documentary. Sometimes that means closing your eyes or trying to visualize something that isn’t there, but mostly, it just entails actively focusing on whatever sound (or sound-related concept) the helmer might be emphasizing at the moment. Structurally, Green was inspired by François Girard’s “32 Short Films About Glenn Gould,” subdividing the movie into numbered chapters (only about half of them are labeled). Frankly, the act of trying to identify and enumerate discrete sounds in a film that contains thousands can feel strangely limiting at times, though it gives audiences a sense of how far along they are in a movie I hoped would never end.

Early on, Green delivers a visual pun, as a hovering drone observes a tree falling in a forest. It does not make a sound — not yet, at least, though Green will return to that footage later, inviting foley artist Joanna Fang to supply the sound effects that make the creak and crash of falling timber convincing to our ears. This is just one example of the ways the director investigates the source of certain noises, although he’s generally more interested in how we receive them, both literally and emotionally. “32 Sounds” wouldn’t be nearly so rewarding if not for a few human subjects on whom he focuses, such as experimental musician Annea Lockwood, who once set a piano on fire to see how it would sound. Green samples from “Conversations,” by partner Ruth Anderson; the 18-minute avant-garde piece is composed of words and laughter lifted from phone calls. Green describes what we’re hearing as “the way two people sound when they’re falling in love,” and I swear I could feel my heart growing bigger as it unspooled.

Lockwood introduces the idea of “listening with” (as opposed to “listening to”) something — a concept that also applies to fellow innovator and theorist John Cage’s “4’33”,” wherein the musician is instructed not to play for 4 minutes and 33 seconds, during which time audiences become aware of other ambient sounds as their attention shifts to the act of listening itself. Cage’s provocative piece is typically “heard” in concert halls, though Green opts for a recording in Harvard Square, where anything but silence fills the space where the music otherwise would be.

Other characters include Nahanda Abiodun, an African American revolutionary holed up in Cuba, for whom a 1979 disco song opens a wormhole in her memory, transporting her back to her involvement with the Black Liberation Army, and Edgar Choueiri, a Lebanese-born Princeton professor focused on three-dimensional audio recordings. Choueiri introduces a dummy head microphone that Green uses for a number of spatial sound experiments throughout the film, but his most impactful scene is one in which he plays a reel-to-reel recording he made for himself at age 11.

Sound can be a powerful emotional receptacle, triggering memories when heard again. And recordings — like the stash of old answering machine tapes Green allows us to hear late in the film — make it possible to travel through time, perhaps even to bring back the dead. The one false note, for me at least, was this scene, which is so personal to Green that he leaves the stage (in live performances). I felt no connection to the voice of his late brother, which perhaps he had not set up well enough, whereas I was a wreck when confronted with a recording from the British Library Sound Archive, featuring the mating call of the last known Moho braccatus, a lonely Hawaiian bird singing for a partner who’d already gone the way of extinction.

Our ears are always working, even in our sleep. They greedily absorb every sound, but without context, our brains don’t know what to make of those cues. “32 Sounds” puts the entire act of listening in context, such that I doubt I will ever hear things the same way again.