Sing like you speak – the ‘folk’ voice, or how to sing like a Bulgarian

I’ve always known that I’m more interested in traditional songs, but I’ve only just realised that it’s the vocal quality that I’m most drawn to.

Bulgarian National Women's Choir by Bruce MacRae

There’s something thrilling and primal about the sound of traditional singers’ voices. How do they achieve that and how does it differ from, say, ‘classical’ singing?