Do you know how to make a gorilla purr?

Terri Tacheny does.

All it takes is a few strums on her harp, and the massive beasts — some weighing in at 500 pounds — race to the fence in their enclosure at Como Park Zoo, sit down and listen intently. In a few minutes, they’ll be doing the gorilla version of a purr.

“The first time, I had no idea what it was,” said Tacheny. “To me it sounded like a growl, and I asked the keeper if I should stop. She said, ‘No. That’s a really good sound. It means that they’re happy and contented. It means that all is right in their world.’ ”

Since 2006, Tacheny, a retired special ed teacher from St. Paul, has been playing regularly for the zoo’s primates, which have become her biggest fans. For her part, she developed such a bond with Gordy, a gorilla that died of heart failure in 2010, that she wrote a song for him. (It’s on a CD of her music that’s sold in the zoo’s gift store.) And there’s an orangutan named Amanda “who has never spit at me.”

That might not sound like much of an accomplishment to most musicians, but when your audience is made up of gorillas, orangutans and monkeys, not being spit at is considered a rave review.

There aren’t many fellow zoo harpists with whom she can share that story. As far as she knows, “I’m still the only one doing this,” she said.

Tacheny started serenading the primates when she was volunteering in the zoo’s gardens (which she still does). She had a chance encounter with Vicki Scheunemann, a conservation officer at the zoo who is heavily involved with the animal enrichment program.

Tacheny, who has been playing the harp for more than 30 years, often used it in her classrooms, where she noticed that playing calming music soothed the kids. She asked Scheunemann if it might have the same effect on the gorillas.

Scheunemann loved the idea.

“We try to enrich the animals in as many ways as we can using all of their senses, so it’s not all just food-related,” Scheunemann said. “She has played for other animals, but I think the gorillas really enjoy it. They all want to be as close as they can to her.”

It’s more than just the sound that intrigues them. They also like the vibrations generated by the plucked strings. When one of Tacheny’s CDs is played for the primates, they don’t react the same way.

“You know how animals can sense an earthquake before it happens?” Tacheny said. “They’re very sensitive to vibrations. They sense the changing vibrations in the air” that are set in motion by the harp.

That’s why most of what she plays is soothing rhythms, rather than songs. “I play patterns,” she said. “I’m like musical wallpaper.”

A woman who overheard Tacheny playing told her young daughter, “She’s strumming a lullaby for the gorillas.”

That’s close. While the music doesn’t put them to sleep, it does calm them.

“There’s a lot of social drama in the primate world,” said Megan Elder, a primate zoo keeper. “The music is very soothing.”

Tacheny has played for the large cats, which also seemed to appreciate the music, she thinks — “They’re cats, so they don’t react much, but they kept an eye on me.” And she has played for the polar bears, which didn’t come off as big music lovers.

“One of them stood up and roared,” she said. “It was the most incredible sound I’ve ever heard. It made the hairs on the back of my neck stand up. If I’m ever playing my harp in the Arctic and a polar bear shows up, I’m a goner.”

A tough audience

The first time Tacheny set up to play for the gorillas, she was ready for the worst. She knew that primates often express their displeasure by spitting or throwing poop at the object of their scorn.

“I was a little nervous,” she admitted. “I had no idea how they would react.”

It turns out that she got the same reception she’d gotten before.

“It was like when I play for a kindergarten class,” she said. “There always are three boys who charge up to the front because they want to be right in front of the harp. It was the same thing with the gorillas. The three of them ran up to me and jostled for a spot. All three wanted to be right in front.”

Her first encounter with Amanda, the orangutan, was an eye-opener, however. Amanda came up directly in front of her and launched a spit that went between Tacheny and Elder, who was standing next to her.

“They spit a mixture of water and food, and it’s not at all pleasant,” she said. “Amanda didn’t miss. Megan told me that orangutans are spot-on in their aim. Amanda didn’t hit me on purpose.”

Elder thinks that Amanda was “firing a warning shot.” Tacheny prepared for a faceful of spit, but it didn’t come.

“She never spat at me again,” Tacheny said, “but sometimes she makes raspberry noises.”

In addition to the gorillas and orangutans, she plays for the monkeys. Each performance lasts half an hour and she only plays about once a month. “If you do it too much they become satiated and lose interest,” she said.

She does it mostly in the winter.

“It’s a special treat for the animals when they’re stuck indoors,” Elder explained.

Musical fate

Tacheny became a harpist by happenstance.

“When I was in my 20s, I sublet an apartment for the summer from a harpist,” she said. “I’d played the piano most of my life, so I started plunking away on the harp.”

Fascinated by it, she paid a visit to a harp-maker — totally out of curiosity, she told herself.

The trip ended with her buying her first harp. Now she owns five.

Unless her husband, Tim Dickinson, is available “to act as my Sherpa” and carry the harp, the petite Tacheny uses a smaller folk harp when she goes to play at the zoo. It stands about 4 feet tall and weighs a mere 10 pounds.

Most of the time, she plays behind the scenes in the area where the trainers interact with the animals, which allows her to get right up next to the cages. (She’s had to get special inoculations, not to keep her from getting sick but to prevent the primates from getting sick.)

“The first time I went down there, I noticed the keepers checking the doors to make sure they were locked,” she said. “I was really glad to see that.”

On a recent visit to the zoo, Tacheny started playing outside Gorilla Forest while the primates were inside working with the trainers. The exhibit space, which opened in the summer of 2013, is a vast, 13,000-square-foot habitat that makes up the largest all-mesh gorilla enclosure in North America.

Tacheny immediately attracted an audience of humans. Meanwhile, trainers hid grocery bags containing food inside the habitat, a common training technique to make the gorillas search for their food the way they would in the wild.

When the gorillas finally emerged, Virgil, the biggest and dominant male, quickly found one of the bags and then charged straight toward Tacheny, violently hurling the bag at the fence, causing it to split open and sending its contents spewing. He came pounding up to the fence, then plopped down directly in front of Tacheny with his nose just inches from the mesh.

All the while, Tacheny never missed a beat. “For primates, it’s all about territory,” she said. “I think he was trying to scare away the people who were next to me.”

In addition to the people milling around, there were other distractions, including PA announcements about a demonstration at Seal Island and noise filtering over from the amusement park adjacent to the zoo. But nothing distracted Virgil, who watched intensely as she played.

“Wouldn’t it be wonderful if every zoo had a harpist?” Tacheny said. “There’s something about a harp that shouldn’t be limited to just humans.”