Backup singers get their time in the spotlight

Background singers Jo Lawry, Judith Hill and Lisa Fischer perform "Leon on Me," in the documentary "Twenty Feet From Stardom."

(CBS News) The anonymous voices behind the music of so many familiar songs are finally stepping into the foreground. Here's Ben Tracy with A Summer Song:

You may not know her name or recognize her face, but you have heard Merry Clayton's voice.

Clayton is one of the most famous women in a rather anonymous line of work: professional background singers.

They are the "friends" who helped Joe Cocker "get by" . . . they made Michael Jackson's made-up language in "Wannabe Startin' " memorable . . . and they are more than just "a little bit" of what made us "Respect" Aretha Franklin.

"I had no problem with being a background singer, a side-ground singer, an under-the-ground singer," said Clayton. "I was just a singer who happened to sing background."

Tracy asked, "When you are singing background for somebody, what is your job?"

"My job is to make them look incredible and sound incredible, because I am gonna be on my thing," she replied.

She started her "thing" back in 1966, when Ray Charles hired Clayton as one of his Raelettes. She went on to sing background for the biggest names in music: Joe Cocker, Neil Diamond, Barbra Streisand, The Doors.

"Anybody you can basically name . . . name somebody," Clayton said.

The Bee Gees? "Yes. 'Stayin' Alive.' That's me and Clydie King."

WEB EXTRA VIDEO: Singer Merry Clayton told Ben Tracy how she had to be talked into performing on Lynyrd Skynyrd's "Sweet Home Alabama."

Lou Reed infamously paid tribute to this often-unheralded role in the music industry, in "Take a Walk on the Wild Side":

"And all the colored girls go: Do do do doo doo do do doo."

"Why do most background singers tend to be black women?" asked Tracy.

"Because of the soul and feel, and the church feel, that we give them," said Clayton. "We came out of the church, and when you come out of the church there is a certain vibe that you have -- it's a spiritual vibe we have that we lay on you, and it's undeniable."

"You are the choir?"

"We are the choir, honey!"

Yet Clayton's most memorable lines would not be sung in church.

In 1969, she got a late-night call from a band she'd never heard of, The Rolling Stones. "I said, who are these guys who wants somebody to get up out of their warm bed, pregnant, and come sing with them?" Clayton said.

The Stones wanted a female voice on their new song, "Gimme Shelter."

Jagger: "Oh, a storm is threat'ning
My very life today
If I don't get some shelter
Oh yeah, I'm gonna fade away."

Jagger and Clayton: "War, children, it's just a shot away
It's just a shot away
War, children, it's just a shot away
It's just a shot away."

Clayton found the lyrics a bit odd: "I could not believe, I said, 'What is this? 'Rape, murder, it's just a shot away'? "

"The Best of Merry Clayton," featuring the gospel singer who has provided background vocals to countless artists. Legacy Recordings

Clayton's searing vocal made the song iconic.

"So I'm just singing and singing and singing, and before I knew it I had a Mick on my right and a Keith on my left, they behind me just carrying on, the lips and everything -- I did it maybe three or four times and I told them, 'Thank you and goodnight,' and I was gone."

Now a new documentary film is shining a spotlight on these women who stand in the shadows. It's called "Twenty Feet From Stardom." Morgan Neville is the film's director.

"I don't think [background singers] get enough credit, because they don't get any credit," Neville told Tracy. "People think being a backup singer is just about singing ooooh or ahhhhhh. But it's about so much more -- the way they sing, the way they do harmony.

"They're just incredible musicians. They're the most incredible artists you've never heard of."

To sample the soundtrack album of "Twenty Feet From Stardom," click on the streaming audio player from SoundCloud below. You may also download selections from Amazon.

One of the film's background singers is now trying to take center stage. On this season of the reality singing competition, "The Voice," four of the biggest names in music fought over Judith Hill.

"For them to say, 'Yes, we love what you are doing now' was really encouraging," Hill said.