Mark Moormann's documentary, "Tom Dowd & the Language of Music," performs an invaluable public service, bringing to light one of the most important -- and until now, largely unlionized -- figures in American popular music. Dowd, for the uninitiated, was the man behind some of the seminal artists of the late 20th century, from John Coltrane and Ornette Coleman to Ray Charles, Aretha Franklin and Eric Clapton. He combined expertise in recording technology with the sensitivity and judgment of the trained musician he was. Part artist, part technician and part coach, he coaxed into being the sounds that would become the signature riffs and backbeats of the musicians he worked with -- and of an entire generation.

And we haven't even gotten to the Manhattan Project yet.

"Tom Dowd & the Language of Music" is a terrific testimonial to a man who easily could have been forgotten except by a few music industry insiders (Dowd died in 2002, just after turning 77). The genial Dowd narrates his own story in the film, starting with his birth in New York to parents who were both musicians. Eventually he trained as a nuclear physicist and, while a student at Columbia, joined the team that developed the atomic bomb during World War II. After the war, the technologically minded Dowd began working at a New York recording studio, where he came to the attention of two young moguls-in-the-making, Ahmet Ertegun and Jerry Wexler; in 1954, the team made Dowd house engineer of their music label, Atlantic Records.

The rest is musical and social history, as these three visionaries introduced the country to rhythm and blues, signing black artists whose hopes had heretofore rested on having their songs recorded by white artists. It was Dowd who helped Ray Charles transform himself from a Nat King Cole sound-alike to the honkin' bluesman he really was, and it was Dowd who, along with Wexler, took Aretha Franklin to Muscle Shoals to help create her signature gospel-tinged sound.

Interviewing the consummate storytellers Ertegun and Wexler, as well as artists such as Charles and Clapton, Moormann creates a straightforward portrait of his subject, throwing in a few tasteful re-enactments and some terrific archival footage of Coltrane, Otis Redding and Booker T. and the MG's. Throughout "Tom Dowd & the Language of Music," viewers come to learn how some of the greatest hits of the past 50 years were created, including the distinctive tom-tom beat of "Sunshine of Your Love" and the classic Clapton-Duane Allman duet on "Layla." (Along the way, Dowd was also pioneering multitrack recording with an assist from guitarist Les Paul.) It's riveting stuff, and the exhilaration with which Dowd recalls those moments of creation is infectious. Moormann deserves credit, not only for choosing a wonderful and deserving subject for a film, but for doing him proud.

Tom Dowd & the Language of Music (82 minutes, at Visions Cinema Bistro Lounge) is not rated. It contains very brief profanity.

Thirty years after recording "Layla," sound engineer Tom Dowd brings up the mix on the soundboard at Miami's Criteria Recording Studios. Tom Dowd helped create the signature sounds of many pivotal artists in 20th-century American music.