in waiting rooms but if history is any guide it will essentially disappear on Tuesday even though it's The radio in stores and in waiting rooms, but if histo Even though music is a big part of the Na te Sloan is an assistant professor of Musicology at the Univers Thornton School of Music.

He's also the co-host Nate, what is it about Christmas music that makes it so popular that makes it so?

NATE SLOAN, thing is that it sounds on radio.

Christmas music is nos It's from a different era.

It uses acoustic instruments.

You hear voices like Bing Crosby and Brenda Lee.

It stands out from business as usual in the American music industry.

JOHN YANG: I mean, you mentioned Bing Crosby and Brenda Lee, I mean, that brings up another point is that so much of the Christmas music is old.

Is comes from like the 40s or 50s.

The top five records on the Billboard Hot 100.

This past week, are all Christmas songs.

Three of them are performed by artists who are no longer Why is that?

Is it that n NATE SLOAN: The oldness of this music is part of its appeal.

Because Christmas, the holidays.

This is a time when you crave familiarity and And so the fact that these artists are the same ones that you've been hearing your entire life is exactly why they've retained such popularity.

JOHN YANG: And it seems like every artist feels the need or has to do a Christmas albu I mean, when I look back, there was a heavy metal album with Alice Cooper.

There was a hip hop album was Snoop Dogg.

And of course a few years ago, there was a Bob Dylan album.

Why do the artists feel the need to do this?

Or why do they do it?

NATE SLOAN: We of Christmas hitmakers.

But if you're able to do Because it means that year after year, people will be listening to downloading streaming, playing on radio, your music.

And if you are able to join that clu JOHN YANG: Well, we can't talk about year after year without talking about Mariah Carey's All I Want for Christmas is You.

This is a song that was written almost three decades ago.

And it's number one on the Billboard Top 100.

What's it -- what explains it staying power?

NATE SLOAN: Well, I think there's a fe I think one thing is you have to credit her as a songwriter.

And as a performer.

Her vocals are incredibl She's able to reach these stratospheric notes th Also, the song was used in a really popular film Love Actually that was released in 2003.

So people watch that film, and that reinforces the popularity of the song.

And I think third, the song has so many hallmarks of classic Christmas music in terms of its instrumentation, in terms of its harmonies.

So it really fits comfortably alongside Frank Christmas greats.

JOHN YANG: Y pieces here.

But pull it all What makes a great NATE SLOAN: Okay, I think you One is there should be some sleigh bells in there.

It also helps if you have a nice string orchestra, some lush orchestral acco you want to have more complex harmonies than you usually hear on the popular music charts.

The kind of harmonies that people like Irving Berlin wrote in his song White Christmas.

That really sends you back to this era of the Great American Songbook, when many of these Christmas classics were written.

JOHN YANG: That's the classics.

Are there any new songs or NATE SLOAN: Well, I've been noting that Kelly Clarkson's 2013 hit Underneath the currently at number 11 on the Billboard charts.

So after a decade of growing popularity, I think Kelly Clarkson is poised to join this this pantheon of Christmas hitmakers.

JOHN YANG: Nate what's your favorite Christmas NA TE SLOAN: I'm partial to Nat King Cole's The Christ Open Fire.

To me this song is It's so easy to sing.

It rolls off the tongue.

Once you start to play it on piano, and I'm a piano, so I love to play during the holidays.

You notice Oh, there's some really clever harmonies and rhythms here.

And I think that keeps us coming back to that song year after year.

JOHN YANG: Nate Sloan of the University of Southern California.

Thank you very much.

NATE SLOAN: