Just in case you weren't already feeling old and hopelessly outhipped by kids who weren't born until Bill Clinton came into office, here's the latest reminder of your fading youth: babies are listening to Metallica.

Yes, Metallica. Infants are rocking out — and dozing off — to thrash-metal classics like “One,” “Enter Sandman” and, the title song from the album many consider to be the best heavy-metal record ever made, ”Master of Puppets.”

“We do a lot of crazy ideas, and so I kind of wanted to do a baby series,” Rockabye Baby! executive producer Valerie Aiello said. “I'm a big rock-music fan, so it just kind of seemed like a fun way to do that.”

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What Aiello and musician Michael Armstrong did was take popular tunes and convert them into lullabies. The songs are performed without words, so the final result sounds something rather like a surprisingly contemporary music box.

It was an unlikely source that gave Aiello the inspiration to turn modern rock into lullabies in the first place. The band Queens of the Stone Age is hardly light listening, but when they released their acclaimed album “Lullabies to Paralyze,” with songs including “Everybody Knows that You Are Insane,” Aiello decided to interpret the album title literally.

“I was a huge fan of that, and I thought it would be a fun idea to do the whole album as a lullaby — but totally cheeky,” she said.

Each band gets its own treatment, starting with Radiohead, Metallica and Coldplay, whose "albums" were released on Aug. 29. Aiello and Armstrong will release more albums on a staggered schedule.

So far they plan to cover the Pixies, Pink Floyd, Tool, the Beach Boys, The Cure, Led Zeppelin and Nirvana (the idea to cover the Nirvana song “Rape Me” was quickly nixed even when it was suggested the title could be changed to “Bathe Me”).

Requests to bands for interviews went unanswered. A representative for the Pixies said that the band couldn't comment as band members and management knew nothing about the project besides what they read in media reports.

Not surprisingly, among the first bands the pair covered were those that tend toward lusher, more orchestral sounds.

“The first album that we did was Radiohead, because we knew the fans would like it even if this was a bad idea, and, I don't know, Radiohead is super-awesome,” Aiello said.

“Pink Floyd was the first classic-rock one that we tried, because we just thought it was really beautiful and it was not much of a stretch. Pink Floyd's really tranquil and nice. The Beach Boys was more like, you have to imagine that and know what it's going to sound like.”

Less obvious are songs like Metallica's “Battery.” The original features such decidedly un-baby-friendly lyrics as “Lashing out the action, returning the reaction/Weak are ripped and torn away/Hypnotizing power, crushing all that cower/Battery is here to stay” and “Pounding out aggression/Turns into obsession/Cannot kill the Battery/Cannot kill the family.”

As a lullaby, the only lyric that still applies is the word “hypnotize.”

“I wanted fans to see and say, 'I can't believe they did that,'" Aiello said. “Everyone asks why Metallica, why Tool. We never really thought it was weird or maybe we're just crazy. We just thought it could be pretty.”

That need for a melody is why Aiello and Armstrong have so far decided not to take up friends' entreaties to create lullaby versions of rap music.

But New Yorker Vanessa Pineda and her nearly 1-year-old daughter, Ava, were lukewarm about the lullabies. They listened to the Coldplay, Radiohead and Metallica albums.

"At first, Ava bounced once or twice to the Coldplay CD. But then nada for the rest of the music," Pineda said. "I found all three too electronic-music sounding, similar to Disney World's Electronic Parade sound. I listened more closely to the first half of Coldplay, but then went through the rest of the tracks without listening to the whole thing, just to see if anything sounded different. Nope. It all basically sounded the same."

Pineda said that, ultimately, the music probably wasn't soothing or interesting enough for infants, and might actually get on the nerves of adult listeners.

"As far as lullabies go, I don't see Ava falling asleep to them or really enjoying them in the
background," she said. "It's this fake sort of electronica sound that eventually got me sick of the
Baby Einstein series. If I want to listen to classical music, why would it be one made to sound like it's coming off a synthesizer? "

Musicians were skeptical that the Rockabye Baby! albums would both remain true to the spirit of the original songs and still actually lull babies to sleep.

“Musically, it was nice, but personally I didn't get it,” Tater Read, bassist with the New York City band Kinopalatsi, said. “It was fine, but I couldn't listen to more than five minutes of it.”

Read reserved more vitriol for what he perceived as the albums' intended audience.

“Why would this be appealing to babies more than regular lullabies? It's for the set of New York City hipsters who give their kids mohawks and dress them in punk-rock jumpers,” he said. “It's cashing in on this set who want to maintain their hipness while having kids. These people are self-absorbed idiots. Are the mohawks and punk-rock lullabies more for you or your child?”

Aiello acknowledged that the albums are aimed squarely at parents, not their infants.

“Babies aren't going to go shopping, so it's basically for the fans, for baby showers or for superfans who have to have everything,” she said. “It's supposed to be sophisticated, to be funny.”

And in her personal experience, she said, babies seem to like it just fine.

“I've been to parties and put the CDs on, and it's for anybody there,” she said. “I've played it for babies — I think one crying baby totally paid attention and then fell asleep after the Coldplay.”

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