It's been four years since Annie Lennox's last solo album, "Bare." But that's better than the eight-year gap between "Bare" and its predecessor, "Medusa."

It's been four years since Annie Lennox's last solo album, "Bare." But that's better than the eight-year gap between "Bare" and its predecessor, "Medusa."

"I'd like to be more prolific with my work," Lennox, who releases her fourth solo album, "Songs of Mass Destruction," on Oct. 2, tells Billboard.com. "I think perhaps in the future I will be more (prolific) -- perhaps as my home life changes, my children start to get a little older. I'm also going to have my own little studio near at hand, so, I think, the future's bright."

Lennox recorded "Songs of Mass Destruction" in Miami with producer Glenn Ballard, who she was introduced to by Eurythmics partner Dave Stewart. "I took us six weeks in all to record, and every day was a great pleasure," Lennox reports. "It was a long call, but it was pretty calculated. I was pretty sure it would work, and it certainly did."

The album's centerpiece is "Sing," which was inspired by Lennox's involvement in Nelson Mandela's 46664 and Treatment Action Campaign against AIDS. After writing the track, Lennox recruited 23 of her female colleagues -- including Madonna, Faith Hill, Celine Dion, Pink, Fergie and Bonnie Raitt -- to add backing vocals.

"I deliberately set out to write a song that could be an anthem," Lennox explains. "Because the incidence of HIV AIDS is on the rise for women, especially in the pandemic across the whole of the African continent, I thought perhaps I could be of benefit by writing a song and empowering those women who do not have an international voice."

"I thought that if I could invite other female artists to join with me, that would be a really strong statement," she continues. "So I sent out a lot of letters to various artists that I thought would be appropriate, and they all came back to me very positively. I'm so glad they've given me their voice and their endorsement of the issue."

Lennox begins a 16-show North American tour to promote "Songs of Mass Destruction" on Oct. 8 in San Diego.