Before you listen to this BBC podcast, I'd like to quickly tell you about some others.

My name's Andy Martin and I'm the editor of a team of podcast producers at the BBC in Northern Ireland.

It's a job I really love because we get to tell the stories that really matter to people here,

but which also resonate and apply to listeners around the world.

And because the team has such a diverse

range of skills and strengths, we've trained journalists, people who love digging through

archives, we've got drama and even comedy experts. We really can do those stories justice. So if

you like this podcast, head to BBC Sounds where you'll find plenty more fascinating stories

from all around the UK.

You're listening to a programme from BBC Radio 4.

From the first moment that the singer's come in,

it's a dissonant, discordant howl of maternal grief.

It's in a minor key, it's an F minor.

And the baseline just goes,

bum, bum, bum, bum, bum, bum, bum, bum, bum, bum, bum, bum, bum, bum, bum, bum, bum, bum, bum, dim, dum,

dumb, just like that.

There's a very dark, solemn introduction,

and then you hear that opening, star,

and then the second voice comes over, star.

The singers take it in turns to cap what the other one is doing,

star, star, star, star, star, star, star.

And that manages to be tremendously beautiful and unbelievably tense at the same time.

...