It is peculiarly human to sing, and to sing together. It is a heartening exercise when done communally on a theme you believe in, as the protest marchers for civil rights understood in the ’60s with “We Shall Overcome.” Such singing was not the same as Doo-wop entertainment or pop songs with the Supremes orchestrated by the Motown machine. Street singing had a different cachet too than Fanny Crosby’s old-time revival hymns. If you yourself enter a non-professional group singing a song that is solid and well-known, it invigorates you.