Tattoos have been a form of self-expression for generations, tracing their roots back thousands of years. But with the advent of soundwave tattoos, that expression can take a more personal note.

The concept came from a California company called Skin Motion, which developed an app that can read a soundwave stencil tattooed on skin and play back a recording over a smartphone. Users upload a short recording to Skin Motion, which creates a waveform design stencil a tattoo artist uses to apply the ink.

Shane Hallock, of Ritual Addictions Tattoo Studio in Glendale, is one of only four soundwave tattoo artists licensed through Skin Motion in metro Phoenix. Hallock, who has been doing traditional tattoos for years, said he was intrigued by the concept once he saw how far Skin Motion had advanced the technology ahead of its launch last year.

“I saw a post probably about two years ago that they were doing this new thing with tattooing and soundwaves and making it audible,” he said. “I wasn’t too interested in it at first, but my interest developed more and more through the years. And then when I checked in on it again this past December, I thought that I had to give it a shot.”

Since then, Hallock has done dozens of soundwaves, but one client was especially important.

His wife, Caitlin Hallock, got a soundwave of a voicemail her late mother left Caitlin on her birthday.

“It’s just a different type of tattoo,” Caitlin said. “I have other stuff of her, but the sound of her voice, it’s just totally different than anything else that I have on my body. It means so much more to me because it’s her voice, and I can hear it, and it’s on my skin.”

For Caitlin, it’s a gift that never gets old.

“It took 24 hours to activate,” she said. “But I woke up for work at four in the morning, and I went and I tried it, and I was late for work because I kept playing it over and over and over again that morning.”

And for Shane, he said being able to give his wife something so special is a feeling he’ll always cherish.

“It means a lot to me to be able to tattoo my wife,” he said. “Especially giving her the soundwave of my mother-in-law’s voice that passed away, because she was very near and dear to us and has always been there with us through thick and thin.”

The company charges $39.99 to activate the tattoo for the first year and $9.99 for each additional year.