Donald Lee Hackett, a singer and guitar player with the Roving Trio, heard the pitch and went on the trail with Gore, sometimes bringing his band.

CNN: Excerpt: 'The Prince of Tennessee: The Rise of Al Gore'

Producer Jason Samel had been walking around Zucotti park in the early days of the protest when he was blown away by a singer-songwriter playing on some steps with a guitar and a harmonica.

FORBES: Occupy This Album: Music Legends Make Record to Support Occupy Wall Street

Take a Portuguese guitar, a soulful singer and a generous dollop of tender, world-weary melancholy and you have fado: the music that has been the soundtrack to Lisbon life for centuries.

BBC: Nine culture-filled weekends in Europe

But perhaps its biggest experiment of all was taking a cute pop tune from the '60s called "Spanish Harlem" and asking a white British singer to perform it, with only a 1932 vintage guitar as backup.

NPR: Look What's Growing in Spanish Harlem

The uninspired, generic Hollywood score often makes the premise feel preposterous rather than moving, but there are some high points, including a gorgeous Michael Hedges tune that gets passed off as an original by August (which he plays the first time he picks up a guitar) and a gospel number featuring a solo by the preternaturally gifted young singer Jamia Simone Nash.

NEWYORKER: August Rush

The singer songwriter violinist pianist and guitarist says she doesn't come from a particularly musical family although her dad plays the guitar.

BBC: Lancashire - Joni hits another high note