Walking out of Morgan Neville’s documentary “20 Feet From Stardom,” you may come to appreciate the almost existential crisis of those talented professionals gathered around microphones just off to the side behind your favorite lead singers/bands. To be able to sing (and I’m talking about soulful “sanging” here), to meld your voice in perfect harmony in order to bolster a star without seeking attention and adoration or a chance to step forward in your own right is a mighty tall order, and it might take an even stronger, greater talent.

There is some aspect of the issue for background vocalists that stands as a precursor to the situation freelance writers and critics found themselves in around 2005. Heralded advances in technology created a situation where unique skill sets became open to the masses –in each case, what we’re talking about involves “voices.”

From the dawn of rock ‘n’ roll, raw lead vocals called out from musical arrangements seeking a counter, a response to the emotion, the righteous fire. Background vocalists claimed that role. They were likened to the choir behind the preacher serving up the fire and brimstone Sunday mornings. But somewhere along the way, someone (Phil Spector) decided to push the background, in the form of an earth angel (named Darlene Love) to the fore – although not all the way into the spotlight because that would have meant crowding himself out the frame.

While Love endured struggles with Spector, a rising crop of singers settled in behind what would become the classic rock ‘n’ roll practitioners of the era. Mick Jagger and the Rolling Stones called forth the likes of Merry Clayton (who sang duets with Bobby Darin), Claudia Lennear (formerly one of the brazenly sexy Ikettes behind Ike & Tina Turner) and Lisa Fischer (who has performed behind everyone from Luther Vandross to Sting and won a Grammy as a solo artist). It seemed as if this golden age would endure forever.

But the heydays of the 1970’s and 1980’s gave way to the 1990’s and the emergence of backing tracks that allowed lead performers to multi-track their own background vocals. Later still, tuning effects cleaned up off-key vocals at the touch of a button. And all of a sudden, the lights dimmed for those who hovered in the wings.

One of the more telling stories in “20 Feet From Stardom” is that of Fischer. We see her later in the film, in the studio with Sting, going through an improvisational, wordless segment, scatting, raising her voice to the heavens. It is a thing of creative beauty, in some ways more stunning than Sting’s lead, and he knows it. More importantly though, he encourages her to go with it and follow her muse. He appreciates that he and this song – when performed live – will be riding her coattails; Fischer will be the engine taking this moment home. Sting talks honestly about what Fischer provides him on tour, and Jagger seconds those sentiments. Fischer has had a standing role in the Stones’ tour since 1989.

We see and hear this phenomenal talent doing what Fischer does best, but Morgan allows us to sit alongside her as she lives in-between. She might be the best example of someone perfectly suited to this life. The film challenges us to leave the theater, race home to our music collections and begin a quest to find Fischer and a host of other performers who have changed the way we respond to the music we love.