FORT MILL, S.C. — About the only quiet places in the headquarters of Muzak Holdings LLC are, believe it or not, the elevators.

The omission is intentional. Muzak management wants visitors to know that the company has abandoned those milquetoast renditions of pop songs that got toes involuntarily tapping in elevators everywhere.

But while Muzak Holdings spent years reinventing itself by sales to restaurants and retail stores of custom "playlists" — of real songs, not elevator-music versions of them — the company sank deep into debt. Now Muzak is under Chapter 11 bankruptcy protection.

"This was a financial situation that was looming for 10 years," said Bruce McKagan, Muzak's vice president of content services. "This just happened at a devastating time for everyone."

It doesn't appear to be the day the Muzak died. The company plans to emerge from bankruptcy fairly quickly as it restructures its $436 million debt. Muzak's filing cited assets of $324 million.

Meanwhile, Muzak has been cleared to keep operating its library of more than 2.6 million songs.

Even so, Matthew Dundon, managing director at Miller Tabak Roberts Securities in New York, said it will be hard for Muzak to achieve steady growth in the tough economy as retailers close. Already, Muzak was having trouble growing; its 2008 revenue of $249 million was essentially flat from 2007.

"The wind in 2009 is anywhere but at their back," Dundon said.

Muzak tried last year to merge with rival DMX Inc., but the deal fell apart as the credit markets soured in September.

What's so costly about the business? After Muzak switched in the mid-1980s from playing cheesy remakes to packaging songs by their original artists, it accumulated much of its debt by buying out franchisees. Muzak also pays more than $26 million annually in royalties, licensing and other fees.

Those tunes envelop Muzak's workers the moment they pull into the parking lot and throughout the headquarters. On one recent day, Prince's "Kiss" rang through the lot. In Muzak lingo, songs are tucked into one of nearly 90 playlists, or "programs," and "Kiss" is on one called "The Boulevard," for adult R&B.

The offices are designed like a European village, complete with a central square for concerts by local acts. In one building, thousands of plain white shoe boxes line the walls, storing the numbered CDs from which songs have been ripped.

Nearby, things are quieter among the audio architects, who customize music layouts for such clients as Ann Taylor, McDonald's and Caribou Coffee.

Audio architect Steven Pilker explains that sometimes a customer wants a simple playlist — say, all country and western. But much of the time, Muzak's artists get to create.

"That's the fun part," said Pilker, a fan of electronica.