Who was this amazing singer in Washington Square Park, New York?

Just returned from a holiday to the US, which included a trip to New York. We wandered around Manhattan on the weekend after 4th of July and ended up in Washington Square Park, where we chanced upon a band whose singer had the most amazing voice, singing 1920s-30s blues/jazz-style songs. Her style was so close to the singers of those times that I could almost hear the scratches on a well-loved and oft-played record.

We were transfixed by her voice, but unfortunately someone interrupted with a drumming solo down by the fountain so she had to stop as it threw her timing off. I was wondering if anyone knew the name of the band, as I’ve forgotten it now. Maybe they have a website with some samples for download. Hopefully someone on the Dope would know who I’m talking about?

On another note, I was completely taken by surprise by the helpfulness of native New Yorkers. From time to time, when I was consulting a map, someone would pop up with directions, completely unsolicited, and a kind word or two. Like, wow.

Thanks for your help!