Murmurs Heather Grody and Leisha Hailey are not only co-songwriters and co-musicians, they are best friends.

So if one interrupts the other during an interview with a quick criticism, no offense is taken.

“You’re using the word fun too much,” Hailey budded in during a phone conversation Thursday afternoon.

“Well, I guess I’m just in a good mood,” Grody said. “Everything seems fun.”

Grody’s beatitude hails from the lifestyle she is currently abiding — her favorite facet of being a musician — life on the road.

But this tour is different than others on which the acoustic duo has embarked in its nine years as a team. The girls are touring with a full band in support of the most complex Murmurs album to date.

“Blender,” released in July on MCA, is The Murmurs’ third major label record. Unfortunately, it is only the second to be adequately promoted.

“Pristine Smut,” The Murmurs’ sophomore effort, was released at a time when MCA was going through staff changes, and The Murmurs suffered the dreaded “lost in the shuffle” curse.

“People were asking us if we were back on an indie,” Grody said.

But The Murmurs were not about to let “Pristine Smut” perish — at least not the good songs. Grody and Hailey had continued writing songs they were happy with and decided to record them and release them with the better “Smut” tracks on a new record.

The outcome was “Blender,” which was partially produced by K.D. Lang and includes new material co-written by Charlotte Caffey and Jane Wiedlin of The Go-Go’s.

“Growing up, The Go-Go’s were our teen idols,” Grody said. “Just the fact that we got to meet them was cool. We set out to write a Murmurs/Go-Go’s song — fun pop music — and that’s what we did.”

Lang’s work on the record was also a dream come true for Grody.

“She’s a hero of mine,” Grody said. “She’d been to some of our shows and came up to us one night and asked if we would be interested in her producing a Murmurs record. I said, ‘Oh my God, are you kidding?'”

Lang instructed the former New York University classmates on the secrets of playing with a full band. Her artist’s perspective also allowed The Murmurs more freedom than on past records.

“It was a very nurturing experience,” Grody said.

Grody and Hailey have been friends for a decade and have been playing music together most of that time.

“We haven’t stopped playing since the day we started,” Grody said.

The duo honed its music in the bowels of the Manhattan subways, earning a few bucks, but mostly running away from police.

It wasn’t long before The Murmurs released an indie record which caught the attention of MCA.

The group eventually recorded its self-titled MCA debut, which went on to sell over 75,000 copies and introduced The Murmurs to MTV and modern radio with the stick-in-your-head single “You Suck.”

“We had a mentor who both of us really admired and who got us on an indie,” Grody said. “But he turned on us. He didn’t want us to get signed, and we had made a bad deal with him that we’re still paying for.

“So Leisha wrote a song about him and played it for me as a joke,” Grody explained, “and it sort of became our theme song, and radio stations started playing it.”

The Murmurs still play the tune, although Grody insists there is no anger left in it. “You gotta let go,” she said. “It’s all for fun.”

Fun — Grody’s word of the day, and an easy one to overuse when you’re doing something you love with someone you love.

The Murmurs play an all-ages show Sunday at People’s Bar and Grill at 7 p.m. Tickets are $5.