OK. So the Philly accent isn't "fading," per se.

"It's just changing in a different direction from where it was going before," said Josef Fruehwald, one of the University of Pennsylvania linguistics researchers behind a study we reported on yesterday. "It was more Southern-influenced before. Now it's changing to more like other Northern dialects."

Basically, a handful of vowel sounds are getting more "Philly," while others are becoming more generic.

That's the top-line finding from Fruehwald and Penn linguist William Labov. They've developed new technology for crunching decades of voice recordings — audio that Labov's students have been gathering from across 89 Philadelphia neighborhoods since 1972.

So to explain which parts of the Philly accent are changing and how, let's go to the archives.

To the tape

Meet Celeste (a pseudonym). She was 42 when this was recorded in South Philadelphia in 1973:

 

Now forget those amazing "dances" at the end there. Focus instead on the "o" in "soda."

In the '70s, the researchers say, two types of "o" sounds were getting increasingly extreme among native Philadelphians.

Typing won't do it justice, so here's the description from Fruehwald:

 

"Those kinds of pronunciations are largely similar to Southern dialects," Fruehwald explained. Labov says he's long called Philadelphia "the northern-most Southern city" because of its linguistic quirks.

OK, so here's finding #1: That rising trend line of extreme "o" sounds actually reversed, starting with Philadelphians born in the '50s and '60s. Those "o" sounds, strongly influenced by Southern dialects, steadily became more Northern, more generic. (A note: Labov and Fruehwald say their study examines the speech community of white Philadelphians with deep ties to the city.)

Now here comes finding #2: While "o" sounds have gotten less distinctive — less "Philly" — an "i" sound has done the opposite.

For this, we go to 1985, to a gentleman born in 1901:

 

"That's how Philadelphians spoke around the turn of the century," said Fruehwald. Accents are forged in early childhood.

Fruehwald then fast-forwards to a man born in 1991:

 

"This is the new, very clearly Philadelphian sound," said Fruehwald.

That "i" thing, the researchers say, follows a straight trend line: almost all native Philadelphians marching 100 years in the same linguistic direction.

"It doesn't make much difference whether you're male or female, whether you're educated or less educated. Everybody moves together," said Labov. "So that was one of the most astonishing things we discovered in the first view of this hundred years."

Now you may be asking what the point of all this is.

Labov and Fruehwald say there's no clear answer for why the Philly accent has zig and zagged across the 20th century. But Fruehwald, a Northeast Philly native, does offer this.

"These accents are valuable to us as linguists to figure out what's going on," he said. "And to the extent that we can spark any pride in people for the accent and dialect that they do have, that's a bonus."